How much to charge for weaving commissions?

People who sell their weaving, how do you work out pricing? I don’t plan to open a shop or anything, I’m firmly against turning my fun little hobbies into work, but I’ve got someone interested in buying a blanket from me after seeing a couple I made as gifts for family members.

I’ve heard of charging upfront for the price of materials, and then charging by hour at the end. I haven’t timed myself to see how long it takes to create the warp, dress the loom, weave, and finish, but all in all I would estimate around 20 hours.