The 21-year old New Zealand striker is currently on a three-month loan with the Lions who are keen to purchase him permanently after his performances in scoring eight goals in the Championship so far this season.
Millwall have already made two offers for Wood with Berylson claiming the Baggies are trying to spark a January bidding war with a number of other clubs interested.
"They told us £500,000 and I said fine. They said £1million and I said fine. So I've gone for it already - I'm done. That's it," said Berylson.
"For us, it's a take-it-or-leave-it offer. We're not going to increase it but I'm sure West Brom are thinking about an auction.
"If we take our bid off the table, which is worth well over £1million - that's not including a sell-on clause either - and West Brom end up selling him for half that in the future, they will look stupid. That's the biggest danger really, looking stupid.
"I know Huddersfield are in there but Chris has a flat in London."