Like Ken says, poo-poo on buying swap meet engines. Most of these guys want top $$$ for JUNK! If you are a serious collector or know exactly what you are looking for and can bargain, that is another game for fun or profit and so go for it.

Now here are some current prices from the tall place in the sky, and some are really good. Check them out.

O.S. 46LA w/Muffler Natural 67.99 The 40s are gone. This engine will fly an avistar very nicely. Your instructor has to know air-bleed carbs (very easy and super dependable once properly set) and the shaft is a bushed bearing, but if you use a good oily fuel you can get 40-60 hours before it throws more fuel out the shaft than it burns.

O.S. 46AX ABL w/Muffler 109.99 They be proud of this one.

Thunder Tiger Pro .40 Ball Bearing ABC w/Muffler 84.99 Great little engine, the darling of the Club 40 racing crowd, due mainly for its superior idle as those racers have to go from a non-held standing start. Not cheap, but a good engine.

Thunder Tiger Pro .46 Ball Bearing ABC w/Muffler 89.99 This will equal the OS 46 in about everything except price.

GMS .40 ABC BB w/Muffler 59.99 Fast powerful engines. Touchy to handle especially at first as they are true ABC which some inexperienced have a problem with the engines as they require a somewhat different approach to operation.
LXDXL5 GMS .47 ABC BB w/Muffler 64.99 same above. Both have tuned mufflers which adds to the touchy operation.

Now my favorites are the Super Tigres 40 ($50) and 45ABC ($65 and an easy ABC). Good prices but 45 is out of stock until next month. If one has the patience and know-how to break that little 40 in, and adjust the carb (really needs a restrictor which I can make) one can enjoy many hours of trouble free flying.

Screw swap shops. Why pay for someone else's mistakes?