I can't say I'm in the market for any sketches right now, but it looks interesting. I'm probably to paranoid to buy something like that though. I'd definitely wonder about the origin, reference used, reason for selling, etc.

I would also be interested, but like Thoman my paranoid nature would stop me from making a serious offer. I would worry about not being 100% sure of the sources used and so on.

Ah, I see. There are some better paying sites to the right if you are looking to still sell them as stock art. GL, Drawshop, Clipartof, Toon Vectors, Cutcaster or there is always the self-hosted option. I'm not sure what you are looking to get per sale, but most of these sites average a lot more than $.30 per sale. You could also go outside of microstock too.

As far as selling full rights to a microstocker, I would assume you wouldn't get a very good price. I'd probably try to buy them for a dollar or two per sketch. They are worth a lot more than that, but I wouldn't be confident I'd earn my money back if I invested much more.

sell them on ebay

Nice sketches but it looks possibly like some children's book illustration concept that never went beyond the sketch phase.  ebay may be a good place.