I just went to a swap meet and blew out everything I had. My intention was to unload, and I did. I think your prices were fine, and if I wanted a Sprint crankset, I'd go the $30. I know nothing about mtb RD's, but sounds like a good one. I like swap meets, if there's bargaining going on.

One funny aside: I had a nice DA 7400 front hub laced to a worn Matrix ISO rim, stainless spokes in great shape, and the DA 7400 skewer. I priced it at $5, and the guy had a $10. I only had $4 in change, so the guy waited around for my wife to get back from the snack shop to get the extra $1. The skewer was worth more than $5. I sold new tubulars for $5, used for $3, and a guy wanted to negotiate on a Gatorskin about 1/3 worn for the $3. Gotta love it. When all was said and done, I moved my stuff to the co-op's table, put my Shimano BL400 levers ($5, like new) in a bag with my Transit wedge bag ($2) and went home with two tables, a nice dinner earned.

There was a whole group of bike messengers who put a bunch of tables together and sold stuff. Boy, those guys can wreck components, but they were fun to be around. There was a flipper next to us with a slew of mountain bikes, and even my wife could tell he was full of it, listening to him explain stuff. He sold 2 bikes. His prices were decent, but the sales pitch was disingenuous and he was constantly fixing the bikes so they could be test-ridden.

One downer note, a seller was there with stuff left over from his bike shop that didn't make it.