As SSS says you just need the cash to put the first offer in, the money is not taken from your account until you buy the player. So in effect, if you have 100M, for example, you can bid on 6 players worth 95M each and still win them but you will go into negative and have to get the money back by selling players or getting money by another way..... if that makes sense (too many cans on a Sunday...lol)