I would be concerned with WHY they want to sell them at all, although I don't know what your definition of expensive would be. It is much more cost effective to keep and breed the adults that you have spent years raising, rather than sell them, even for a relatively high price. Just do the math of what one average clutch would sell for wholesale of a particular morph, compared to the usual cost of adults. Sometimes you can luck out on a great deal when somebody is going to college, getting married or divorced, etc. That's what to look for, if you can find it. But you just as likely might find somebody who is trying to get rid of old or poor breeders without mentioning the whole truth to you. If you buy from somebody like Rich, you should be fine on the truthful part, but I doubt that he would sell them cheaply - you would have to check and see what you consider expensive.
I very rarely buy adults myself. I generally want to know the history of the individual and to be assured that it has grown up with the same conditions as the rest of my colony.
Just be cautious - good luck!