Let's turn it around a little. Let's assume you are the artist. Someone approaches you about doing work for you. What's one of the first things you'd ask? "Show me what you can do for me".
Your answer is "trust me".
I don't think it's unreasonable for a customer to want to see samples of what you can do on the media you say you'll be doing it on. We've spent quite a bit over the years on materials for this type of thing. If you can't provide a sample of your work, why would I do business with you? I have nothing to base my decision on, other than your word, and being we just met 10 minutes ago, I don't know what your word means.
Find someone in the area and buy a few yards of material, print him some samples, and move forward. It may or may not work out, but you certainly don't have to spend a ton of money to make a couple of samples. Heck, sub it out to someone that has the material. Doesn't matter, just get them a few samples.
