This is the problem with sellers and buyers alike. I receive a message every now and then asking if I can make certain things - they never say they intend to buy, it may not be what they want, but I go ahead and make the piece, just to see if I can. I won't reply with "yes" if it turns out that I can't, and I won't reply with "no" if it turns out I can, and I'm good at it.
I always make a piece for the enquirer to see - but she never once said she was interested in buying one.
I frequently fell for this, and other sellers do too. You have to take messages like this for face value. They're just asking if you have something, or if you can make something. It's just not right to charge someone just so you can try it out if you already have the materials, because if they don't like it or you can't do it the way they would like it (afterall, they're the ones paying for it) then they'll want their money back.
In the future, don't be so quick to assume a sale. If someone asks a question, answer them, and think nothing more on it. I was asked recently if I could make tiny owls for my jars, and I tried it out before answering. I could, so I told her, showed her a picture, and left it at that, since she never said she was looking to purchase. I've created a custom listing for her, as she is interested, but no money has exchanged hands yet. And if none does, then I'll list the owl as a piece for anyone to purchase, just like everything else.
The only time I think you should charge someone is if you don't have the materials and don't actually know if you can make it, or if the item they want to see isn't something that you could sell to anyone else - like a name, date or face or something.
These are just my opinions, anyway. It's your shop at the end of the day and you should conduct business as you see fit. But everyone needs to remember that questions are questions, no more or less, and if you choose to go ahead and make something then it's your decision.
