The free/fee model is pretty common. I have a lot of quality software that I can use for free as long as it isn't used for business. If you're going to make money, why is it wrong for the creator to want a taste? Your reference to autographs almost sounds like you think this person is some kind of diva for placing a value on their work for commercial use, but are you not expecting to be paid for your work?

Adding price tags to free items would probably only potentially confuse what is probably the vast majority of people who have no intention of commercial use. People working at that (commercial) level should be familiar with useage fees and assume they would apply if it is clearly marked for non-commercial use only - assuming the creator allows commercial use at all.

I'm wondering if they had said $2.00 you'd be upset. Is it the principal or the price? You were willing to offer your item in exchange so it doesn't sound like you are against the idea that some payment is appropriate.

I think of it in terms of fairness over and above commercial or legal stuff. If I lend you my lawnmower for free cuz you're broke or I'm just a nice guy, it's one thing if you cut your yard. If you make $200 cutting other folks yards, then we have no contract but it would be fair for you to give me a taste, no?

I'm not familiar with the commercial art world, but I bet they don't think such arrangements are odd or out of place at all. Are you overly sensitive - I don't know. maybe not sensitive so much as unrealistic.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken