Lots of people do/have done that, but YMMV. I prefer to source products I can inspect beforehand. You never know what your buying online. Lots of bait and switch grey market goods sold such as retail versions from foreign countries, which is a big problem in certain categories. Also condition is often an issue. I dabbled in OA on Amazon once and ordered iPod cases on clearance from goHastings. I ordered everything they listed in stock in New condition. They sent me 3, none of which were actually new, they were all open box returns or loose wrapped in some sort of low quality shrink wrap. A few other orders were similar, stuff that seemed like a great deal was actually over graded crap. Only thing that worked was an expensive piece of electronics purchased directly from Amazon and then sold for a profit after they ran out of stock. All in all I found it to be a waste of time. If you source in person 100% of your purchases will be resellable. You won't be wasting time doing returns which is always an issue with OA from any source.