I was Tim Sale’s agent at the time of Heroes.
Tim held back the art, as we wanted to create anticipation for the art. That kinda backfired as the 2nd season progressed, and buyers were not so interested in the art.
It was at that time I started selling the originals. While there was no great rush, I did sell a number of originals, though for not as much as we had originally hoped for.
Once the series was cancelled, that was pretty much the end of Heroes original art sales, at least when I was his agent.
MI