I think I spotted one in '08 for that price, and when I came back a few hours later, it was sold. That happens A LOT to me on Sundays, I try not to sweat it. Convention sellers drive me nuts when they have really awful prices on 90% of their stuff and then have fantastic pricing on something else, I spent YEARS dealing with that crap at the regular Frank & Son semi-weekly shows out here before I realized I had to stop feeding the scalpers.
The guy I got mine from has been in the same place the last few years. He was a row or two from the far north side of the convention, and had some amazing deals alongside some major ripoffs. I got Megatron for $90, IIRC, but he also had GIJoe comic packs for $25 and up which were easily found at retail for $10. I don't believe he's had any Megatrons for the past two years, though.