Thanks!
-VVV
Any site *could* steal your credit card. So could any worker in any shop where you make a purchase. The point is, most of them are not likely to do so.
The site's been in business since 2003, and they're an officially authorized Magic: The Gathering dealer. Those are both reasonably good signs that you could trust them.
The bottom line is, *you* are the only one to decide whether you feel comfortable ordering from them or not. Maybe you could buy a prepaid card to use when you place your order, and that way they won't have access to your real account.
make sure the site direct you to https when you pay for something