How much are you looking to spend? You can get some great new engines for around $50 as stated. You can also get some higher end used for about the same price, but for the money, you are safer going with a new TT .46 or equiv and not the worry about getting someone elses junk. Sometimes you can steal a good used one pretty cheap, but sometimes it is just not worth it. Check the new ones and compare the prices on ebay and RCU and TR classifieds and don't be in a hurry. You will find a deal.