Yes, I was at Otakon a few years ago and the dealer's room spaces were something like $750 each - there were probably about 100 dealers and I think each had about 3 spaces on average. Also, $65 each for extra dealer's badges for employees. That said, I believe the money from the dealer's room mostly goes to cover the expense of having a dealer's room.

But remember that fan conventions tend to run at cost, while the Singularity Summit is a source of revenue for SIAI.