The second page of a market test

[onemoretry]

When a user clicks on a "Buy Now" action on the first page containing the ad copy, what do you recommend using for the credit card details on the second page? To do a true test, I wouldn't want to use plain old text fields, as these will feel insecure to experienced surfers, and I'll probably get a poorer indication of real "sales" if I do so since I'll be turning even savvy visitors away with my creepy orders page.

Using PayPal won't let me bounce back to an "out of stock"-style message without actually charging them something, which is of course infuriating for them and a headache for me. I'd love to hear what others are doing to accomplish this piece of the market test.