There really isn't a market average for hex signs. It really depends on the style, size, artist, and complexity of design. I have seen vintage hand-painted signs by well-known artists like Jakob Zook going for as little as $10. On the other hand, as younger generations get into the signs and make more contemporary motifs, the asking price tends to be much higher. (For example, there is a shop on Etsy called HexyShop that has really nice collection of contemporary motifs and color palettes.) Unique or lesser known also have the potential to go for a lot more...but as always, it all comes down to what the market will bear and what the consumer is willing to pay. It is a very niche market and if I had to guess, it would be hard to make a full time living making or selling them unless you had wholesaling capabilities or had a brick and mortar in the New England states that catered to tourists.