Hey so I haven't had a handheld in years, and the very last game I played was Pokemon Diamond/Pearl. (Lost my DS and games, RIP all those legendaries and other stuff.) And after playing Pokemon GO, I really want to get back into pokemon.

So what are good places to find a good condition used 3DS? I don't really trust ebay, so, eh. And with that in mind, should I buy both Sun and Moon or just one of them? I bought both Diamond and Pearl so I could have the Pearl exclusive pokemon on my Diamond copy, so I want to consider doing the same for Sun and Moon.