I only had one problem with online purchases and that was from a major distributor. They sent me a crushed box (as was the contents) and it took two months to get a refund. I wanted an undamaged item but apparently they didn't have one.
I also only got one complaint selling on ebay. a customer bought a clearly stated "untested and as is" item from then refused to pay and left negative feedback because it wasn't working.
Got a couple nice Guillows kits real cheap off ebay though.