Ask HN: Is this legal?

I created a site that lets people pick items on amazon and crowdfund them.

Lots of sites take donations so I figured this was not a big deal but yesterday someone told me that I am basically acting like escrow or layaway for amazon and if thats the case then I know they would have an issue with this.

I basically collect donations until the amount of money needed to complete the purchase is present and then the item is automatically purchased from amazon.com and shipped to the user that ordered it. Kind of like a kickstarter for stuff.

So my question is:

1. Is this legal?

2. Is this even worth perusing?

--Thx in advance

btw: the site is http://i.crowdfunded.it if the site does not work for some, sorry; amazon limits API calls and I am waiting on the to approve my additional associate tags so that I can have more than 2k queries an hour.