Originally Posted by alvin
You shouldn't really use ebay as a guide: more often than not the best sketches will be kept in personal collections and the mid-quality or lower will end up being sold off.
Best to keep an eye on fan box breaks to get a sense of quality.
I'd estimate that about a third to half of what I consider to be my best sketch cards for "Mars Attacks Heritage," "Star Wars Galactic Files," and "Star Wars Galactic Files 2" never showed up on eBay. Yet the ones I wasn't happy with, but had to turn in anyway, seem to always show up for sale.