My dear spousal unit has been reusing the plastic grocery bags since they first started offering them at the stores (he owns the oldest Comic Book shop in our area!). When I began participating in craft shows, I did the same - and our families all save bags for us.
When I contemplated entering ART shows, however, I started to wonder if I would be the "other side of the tracks" person in the show if I didn't buy new, pretty bags for my customers. I started to check the prices on bags online, and, while I was in the "considering placing an order" phase, we went to an art show (as shoppers/browsers). One item I purchased was an inexpensive pair of earrings for $12 - hey, they had LEAVES on them! Anyway, they wrapped the earrings in pretty tissue paper, placed them in a bowed out cardboard envelope that had a pretty print on it, and tied it with a small piece of ribbon! Was I impressed? Well, actually, sort of, but at the same time I thought A) A tiny bag would have worked just as well and B) The artist would be making more money and/or could charge a little less for his larger pieces if he didn't spend all that for packaging! Between that experience plus the fact that I really couldn't find a bag that would fit my work any better than the grocery bags, I decided against buying any bags.
And, I have to admit, no one has ever looked at us funny or acted insulted because we used newspaper and Walmart bags, from the other artists OR our customers! Maybe ten years ago they would have, but in these "Green" days, it's more appreciated. If I feel that maybe the customer is a little funny about the packaging, I just smile and say, "Reduce, Reuse, Recycle, right?!" and they laugh and nod! I'm really glad that I decided to stick with my reused bags, and I have since discovered several artists who do many of the larger art fairs and still use recycled bags.
Only one problem I can see - most stores now sell inexpensive cloth bags to use in place of the plastic bags for responsible shoppers, which I DON'T use because, of course, we need them to reuse in our respective businesses! Now I feel that everyone thinks I'm not environmentally conscious! (Can you tell I worry a little too much about what other people think?). Also, the idea of a "bag tax" of 5 or 10 cents per bag is being considered for the people who don't use the cloth bags, which I would think was a good idea, except that, again, I need those bags!