There are some very good sellers on ebay, but always check their feedback. If there is to much bad feedback avoid them. United outdoors is one of the good ones and there are several others. None of the heavy volume sellers will have perfect 100% positive feedback because of all the knuckleheads they deal with, but they should be 99.5% or so. Also most ebay purchases are guaranteed to get your item or your money back. I would not be afraid to buy a bow off ebay at all, in fact I have bought several. Warranty work will be done by the manufacturer anyway, so on these cheaper crossbows I don't think there is any advantage to buy them from someone like Lancasters. But hey if you feel better buying from a reputable bow dealer there is nothing wrong with that. As far as the 370 and 390 Mercenary they are a pretty new bow from Crosman and there is not much info out there yet about them. I sure would not be afraid to buy that mercenary 390. I had one on watch for awhile, but ended up buying the Killer instinct Ripper 415. Hope this helps.