I've never had much luck at these shops either although many guys swear by them. Thats ok though because many of these shops dont seem to have much of what I'm looking for these days (45+ chainsaw motors). They seem to alot alot of weedie engines etc....which are a dime a dozen anywhere. I've found ebay and local consignment sales the best. And public sale flyers usually list what their gonna be selling. Many times you can find stuff that is falling apart, but the engines are still good for dirt cheap and you dont have to explain what your doing with it to anyone!
So,your not missing anything....I'd just recommend staying away from those shops(alot will dissagree here,lol) and look for ebay deal, consignment sales, public auctions, and even yard sales. Most people who arent into this RC gig dont understand us and what we do and it always sucks trying to explain it without looking like a nutjob.