Thanks for the suggestions, y'all. I'd thought about the Threads profile field or the User Group access and attached files, but it would still involve manual intervention to process the Paypal orders, which is what I was trying to get away from. (Not like I plan on this thing having more than like 5 orders a month, but still... I'm really lazy!

) It may work in a pinch, though.
Allen, my host has a one-click install for oscommerce, but I haven't gotten around to trying it out yet. Just looking at its website, it looks fairly complicated. But it's probably going to be the first thing I really try to make work, since I won't have to buy anything extra.
Gizzy, that looked to me like it was more for hosting and domain registration, but it definitely has a better-looking website than any of the stuff I found on Hotscripts, so I'll keep digging and see if it can do other stuff besides that.
---Jamin