You never know what the crack is on eBay though, mate. There could be very simple reasons why a retailer that wasn't getting as much traffic to their website as they'd like, or just not enough sales, and they need to generate cash now, would stick stuff on eBay in another name, or through a friend's eBay shop. Then there's the people who know a mate who knows somebody who can get a deal on X thousand units of bla...
For small amounts like that, if they do rip you off, eBay will probably reimburse you themselves. They've done that for me for about 1/2 that much. I can only give you personal experience of SHS shims: totally excellent! Their nozzles are legendary too. Personally I don't like polycarbonate pistons, but for that money, I'd go for it anyway and swap that over with an ali one... if I had a V2 gearbox anyway, but I don't lol!