There's no "if" any more, Ebay will no longer be accepting checks and money
order as viable forms of payment:
http://pages.ebay.com/sell/August2008Update/OtherFAQ/#3
Quoting Michael Hart <imsaicollector at yahoo.com>:
Make sure if you
get paid by pay pal you wait 21 days when Pay pal actually allow you to take
the money from your account