Actually, Buy It Now auctions are no different than other auctions as far as the timing of your payment for them. It does not mean you have to pay for it instantly. Most sellers state in the listing that payment is required within a certain amount of time from the end of the auction. I've noticed it's usually at least 7 days.
The Buy It Now feature is simply a way for the buyer to commit to a preset price ending the auction early.
As for the 'rules are there to be manipulated' attitude, I'm a fraud investigator for a national comapany, so obviouly I couldn't disagree more!! And quite frankly, this 'tactic' is not really a matter of manipulating the rules but is completely against the rules!
eBay clearly states:
Under exceptional circumstances eBay allows you to retract bids. For example:
It's OK to retract a bid if...
*You accidentally enter a wrong bid amount. For instance, you bid $99.50 instead of $9.95.
(If this occurs you will need to quickly re-enter the correct bid amount).
*The description of an item you have bid on has changed significantly.
*You cannot reach the seller. This means that you have tried calling the seller and his or her phone number doesn't work, or you have tried emailing a message to the seller and it comes back undeliverable.
Clearly, 'manipulating' the rules does not fall into exceptional circumstances. I wouldn't recommend this 'tactic' to anyone who wants to avoid being kicked off eBay.