Prefired or if you're feeling brave, Usedairsoft (Usedairsoft has a problem right now with scammers, but i think its more on the seller side. Still, I would exercise extreme caution doing anything there)
Also, as it's not a RIF you could list on ebay as a private seller, Private sales pay no fees now, i tend to sell a lot of my gear on eBay it just takes a bit longer