RX7850
Yes eBay,
However for me, dealing with sellers has yielded alot of problems related to items arriving damage,not at all or not as described. I'd say an issue has happened over the last few months 40% of the time. Not sure how common this is just my experience. Employ due dilegence.
I've bought maybe 50 kits thru eBay and never had a purchase end badly. Here's some things to keep in mind:
1) The vast majority of sellers are good guys who mean well. You can tell a lot about a seller by how he words his description and the kinds of pics he uploads. Almost anyone who has a 99-plus percent feedback rating is trying to do the right thing, though I'm sure there are exceptions.
2) If the item is not as described, the seller has to refund not only your purchase price and shipping but must also pay for return shipping. Every time this has happened to me, I messaged the seller about it and in every case he told me to just keep it and he refunded my money and shipping. Sellers REALLY care about their feedback rating!
3) If the description says that the kit is complete, I trust him. He is the one on the hook if it has something missing. If it doesn't say, I ask him before bidding/buying.
Often the seller doesn't know models and honestly can't tell you if it is complete. But if he uploaded a set of sprue pics you can see for yourself if it's all there. Be wary of offers that don't have sprue pics unless it is described as complete.
4) I had poorly packed model come with broken parts. I still wanted the model, so I asked for a $10 partial refund. He refunded it all.
In a couple of other cases the kit had missing parts but I wanted it anyway, so I asked for a reasonable partial refund and got it.
5) I believe that the seller is on the hook if he didn't get tracking and it does not arrive. I mean, golly, tracking is free if you buy the shipping thru eBay. However, international is a lot riskier, except for Canada which is as safe as USA.
6) I believe that most sellers appreciate a message before you open a return. In general they would prefer to make you happy without involving eBay.
7) Finally, if the seller is not interested in making it right, simply open a return through eBay. EBay generally assumes that the buyer is right and is not amused by sellers who misrepresent their offers. (My wife and I have sold some 2,000 items on eBay so we do know more than we like about returns.)