To give a bit of background, in the 1990s I was the Comics Buyer for Green Apple Books in San Francisco, where I did two very successful catalogs of comic-related books and Pre-Code Horror, Crime and Mad material (including the original cover to Mad #21, 1st Alfred E. Neuman cover appearance).
After Green Apple, I went to Bonhams Auctioneers, where I put together a single-owner sale which set five world-record prices for CGC books in those grades, including a CGC 9.8 Incredible Hulk #181 (final price, $16,500). Here's a GPAnalysis article on that sale:
http://comics.gpanalysis.com/gpaforcomics_newsfeed_article.asp?id=13249
The Bonhams sale convinced me that I can get great results for good material, equal to or greater than results achieved by Heritage or eBay.
Cheers, Ivan