First of all- those are so cute. Second, pricing for a gallery isn't so different from pricing for retail. You're still providing a product for a customer- the venue is just a little different. The spreadsheet that goes along with this article is very helpful:
https://blog.etsy.com/en/2014/how-to-price-like-a-pro/In addition to figuring out the price of materials and labor per piece, take into account the fact that your pieces are made by someone with a particular set of skills (woodburning) that not everyone has. In my experience, I try to price things as dispassionately as possible- having a pricing formula written down on paper makes it easier to to defend if someone tries to haggle with you.