De,
I have never used them, but saved APMEX years ago, just in case. If I'm not mistaken, DueDillinger, a voice from the past, recommended them highly (maybe his post is still out here).
http://www.apmex.com/
I'm actually looking for a place I can sell my old coins and stamps, as well. Have no idea who is a reputable dealer that offers accurate grading and prices. They all claim to give the best prices, blah, blah, blah...