You can let folks know via mic that you have CD's (and mailing list), and to see you after, but not take the featured ppl's prime selling space or use visual materials that are bigger/more flashy than theirs. They might invite you to share space or take turns tending each others' stock. They might buy your CD, too. A word with them, I agree, is in order.

You might also leave a few with the venue w/price stickers to be sold when you're not there, if they're interested in consignments.

~Susan