You know... I was thinking about doing this somehow, except I'd either need to pay someone to use their ticket machine, or become my own official lottery licensed thingy.

Now the interesting part: I'd accept credit cards without a second guess. Why?

First thought is "fraudulent transactions to redeem... duh." Yeah, that's totally true, but here's what you do:

When someone purchases the ticket online, you give them their numbers (obviously); you don't give them their barcode to redeem. Let's say they win: To receive the ticket's barcode, they must present the card they used to purchase. If they don't, well, you've got yourself a winner.