What they are buying is reassurance, and reassurance has turned out to be the most expensive thing on the shelf.
Chelsea paid a reported £117 million for Morgan Rogers, edging past the £116m Manchester City had just given Nottingham Forest for Elliot Anderson, making two Englishmen the most expensive British players in history within a fortnight of each other. And there are still a couple of weeks left to run.
Neither club is buying a guarantee. Both are paying record money to feel like they are.
Add in that nearly every big dugout has changed hands in the last 12 months, and a new manager's opening move is always to buy his own certainty: profiles he trusts, names that quiet the fanbase, players already proven in England so nobody has to explain them.
Then a World Cup comes along, and suddenly every player anyone half-watched for a month feels like someone you cannot live without, and clubs have stopped buying players and started buying insurance policies.
De Zerbi's Spurs rebuild
No one embodies it more completely than Tottenham. These are back-to-back 17th-place finishers who survived on the final day, now transformed into the league's second-biggest net spenders at roughly £158m at the time of writing. Tonali cost an initial £92.5m, rising towards £100m, a club record. Mateus Fernandes cost £85m from a relegated West Ham, Jan Paul van Hecke £52m from Brighton.
That is £267m of hard fees, almost all of it spent importing proven Premier League names, to reassure a squad that spent last season a defeat away from the Championship.
To their credit, they have shopped the bargain special buys aisle too, adding Andy Robertson, Marcos Senesi and Martin Dubravka on frees, which is exactly the sort of sober, low-risk business a club in their position should be doing, and precisely why the nine-figure panic-buying next to it looks so odd.
Roberto De Zerbi insists the work is not finished and that Tottenham deserve to compete at the top, and given the pace so far, you would not bet against another big arrival before deadline day, particularly in attack.
This is not a plan so much as a flinch with a dusty chequebook, and there is something almost admirable about the sheer scale of the ambition. But it could also all be for nothing.
Chelsea and United's prudence or paralysis
Chelsea, the anxiety engine of the modern game, are running the same play with more polish. They finished 10th, lead the net-spend charts at around £181m, and hijacked Rogers from Arsenal, who declined to match Villa's price. It is funded, as ever, by the club's one genuinely world-class department: selling, with Marc Cucurella alone bringing in about £52m from Real Madrid.
The connoisseur's touch is the reassurance signings hiding in plain sight: into all that teenage churn, Xabi Alonso has folded Danny Welbeck and Jordan Henderson, both born in 1990, presumably sold to the dressing room as experience if not pension advice.
And then Manchester United, the counter-case that sharpens the point. Last season, Michael Carrick spectacularly dragged them to a third-place finish and back into the Champions League, with Bruno Fernandes the season's best player after a record 21 assists.
A gigantic club returning to Europe has reinforced, to date, with Andrey Santos for £50m and Youri Tielemans on a £35m release clause, plus a 35-year-old free goalkeeper.
Either this is the calm of a side that believes it knows itself, or the thrift of a club still paying off last summer. Prudence or paralysis, dressed identically.
Even Manchester City are not immune, which tells you how far the mood has spread. Guardiola gone, Maresca in, and the most composed club of the modern era has spent the summer selling Rodri, a Ballon d'Or winner and the best holding midfielder of his generation, to Barcelona for an initial £51m, having had the foresight to hand Nottingham Forest £116m for Elliot Anderson to fill the very hole they had just made.
When City start paying nine figures to steady their own nerves, you know it has got to everyone.
Newcastle breached
Then there's the club being sold for parts to fund everyone else's calm. Newcastle have been comprehensively gutted, and the window is not finished with them yet. Bruno Guimaraes went to Arsenal for £75m, Sandro Tonali to Tottenham for £92.5m, Anthony Gordon to Barcelona, and roughly £236m has come back through the door.
Three-fifths of a spine sold in one window, captain included, from a club that had already failed to reach Europe last season. Eddie Howe is gone, Matthias Jaissle is in, and the reinvestment tells the story cleanly: around £168m spread across six players, almost all under 24.
This is a club forced to swap certainty for hope, moving against the grain of the entire market and not by choice. Until a controlling midfielder arrives, and they are still hunting one, Tyneside is running its rebuild with the load-bearing wall sold off to a league rival.
Which brings us to the wall's new owners, and to the one club secure enough to spend from comfort rather than fear.
Arsenal ended a 22-year drought with 85 points and the division's best defence, as well as reaching the Champions League final. Bruno at £75m is, on its own terms, excellent business. The sticking point is more about where he fits in.
The Brazilian joins a midfield already stocked with Declan Rice, Martin Odegaard, and World Cup winners Martin Zubimendi and Mikel Merino. It's like buying a second oven because the first one is excellent, while the actual problem - a team that still struggles to score in volume - gets a partial nod in Christos Tzolis for around £34m.
Wildcard rumours about Vinicius Junior aside, this is what spending without anxiety looks like, and it feels like a luxury nobody else can afford right now.
Calm on the continent
On the continent, Barcelona have bought Rodri from City for an initial £51m because certainty has a name, and it is the World Cup-winning captain, a coup shaded only by the fact that he is 30 and still not long back from an ACL injury.
City, having sold their certainty, have spent £116m on Anderson to manufacture a new one.
Only Jose Mourinho appears to have grasped that the familiar need not cost a fortune: Ibrahima Konate, Bernardo Silva and Denzel Dumfries have all arrived at Real Madrid for nothing. The smartest operator of the summer, as it stands, is the one paying zero for reassurance.
Italy, meanwhile, has been quietly running the counter-market, hoovering up the players England has grown bored of, with Inter taking Djed Spence and Napoli banking Rasmus Hojlund, proof that one league's discarded uncertainty is another's shrewd bargain.
And above all of them sits PSG, the actual reigning, defending European champions, who have watched the whole circus with the serenity of a club that already has everything it panicked for years ago, and now simply does not need to.
This is ultimately the window where clubs have stopped buying players and started trying to buy peace of mind, and nothing in football carries a bigger markup.
The sides that know who they are are spending lightly, or spending easy, and sleeping fine. The sides that are masking an identity crisis are paying a fortune to feel a bit more sure of themselves, but a briefcase full of cash has rarely calmed a nervous club down completely.
So between now and September 1st, one more club will pay a record fee for the one thing football has never once sold: the certainty that any of this will even work.