Idea: Random purchases, every week, on Amazon.

I have a funny website idea. I looked into it a little bit and am not sure if it's possible, at least with Amazon. The idea was to allow users to sign up and receive random items ordered off of Amazon.com once a week, month, whatever. The user wouldn't know what was ordered for them until it arrived. Why? People enjoy receiving packages in the mail - it's fun. You'd be able to sign up and pre-pay like $100, or however much, and specify your maximum item price-per-purchase. So you could say "do not buy items more expensive than $10". You could also specify the interval for purchases to be made - weekly, every other week, monthly, whatever. You could specify categories to receive items from - not like Books, Electronics, etc, but more like Technology, Fun, Random (ok, perhaps specify books, electronics, and stuff too). This idea would be even better if you didn't have to pre-pay, but could somehow allow the service to make purchases with your paypal account or something. This wouldn't have any real purposes other than to have fun and receive random fun things in the mail. Business model? Amazon will pay you for referrals. Perhaps even include tons of retailers and provide an unbiased selling platform for them. I looked into this and was able to whip up a quick program that grabbed random items from Amazon and took into account categories. It doesn't look like it's possible to automate purchases on Amazon, though. I also don't know how you'd automate buying items for the user unless you made them pre-pay. What do you think? Would be interesting, no?