You have to watch this video. I've run into this I don't know how many times, and I'll bet you have too. Every customer seems to do it one way or another. Tonight I actually had a client send me part of the money for an xbox wrap. Saying "Here's $35, paypal wouldn't let me add anymore funds because my debit card/credit card expired. I contacted the bank and they are sending out a new one. So I'll just send you the other $10 when it comes, don't wait to send the xbox skin though.
My reply, I'm sorry, but unless I receive the full amount, the full skin isn't going out. So I'll just send you the controllers and when the rest of the money comes I'll send the Xbox part of it.
I swear, people piss me off.
Anyways, here is the video.