I purchased a number of CGC graded books, totally about $4,000 from Silver Age Comics. Each purchase I made from SilverAgeComics was completely random in every sense of the word. They simply happen to have the books I was looking for. When I bought his X-men#1 at NYCC, someone pointed to Gus by name and I turned to him and said, 'Hi, I'm the guy who picked up book XXX from you two weeks ago. Thanks!!" So, thankfully, everything has worked out for me with SilverAgeComics and I have no qualms about buying from them in the future.
As a side note: I do NOT buy RAW books online for a number of reasons. So, I cannot make any claims as to how well SAComics is with RAW books. Slabbed books, I have had ZERO problems.
-Issa