Everton boss David Moyes believes the capture of Tim Cahill could be a one off.
Moyes said: "I don't think I'll ever do a bit of business as good as him again. There will always be business done when you pick someone up from the lower leagues but I don't think that will be done in the English leagues.
"You might do it abroad, but maybe not in England again because it's getting harder and the talent is identified earlier on in the lower leagues these days.
"A lot of the problem would be with the price. We got Tim for £1.5million, but you might have to spend £5m or £6m to get the same type of player now from the lower leagues.
"We would not be able to do that these days, and maybe Tim would be worth £7m or £8m. The three or four who might step up from the Championship would be worth big money."