Buy from a Knowledgeable Dealer.... your going to need that Training and Level of Expertise no matter what you purchase.
Local Face to Face has its advantages. If you have nobody near, mail order can save time but make sure there is a limited support from the Dealer. Other areas to purchase are through Clubs, Garage Sales, Pawn Shops,
Forums like this one, Craig's List (be careful though) and of course EBay and Amazon. Again, certain Amazon or Internet Stores don't even touch the merchandise and just have it drop shipped with no instruction or knowledge, then if you Bite, your on your own like so many I've seen on the forums, that need help. Use YELP and On Line Reviews to help with your choice. Our friends at Kellyco, sponsors of this forum, offer a full staff of folks that want to help you make that choice and will offer reasonable support after the sale, but like many dealers, expect you to do some homework by studying the manual.