“Hand assembled and artful” aside, what sounds reasonable is for you to know what your product COSTS to produce, your percentage of profit, what your wholesale price should be, and what you want it to retail for to the public. Obviously selling oneies and twosies is going to cost significantly more than a series production, but if you want to make any money at this you need to cost this out on a production basis. Letting your “customer” tell you what they expect to pay will get you out of business pretty quickly.
Read this → Manufacturing my tablet case
You did not mention where you live, but if you are not collecting “sales tax”, and do not have some form of “resale permit” from your state (U.S.) which authorizes you sell without collecting sales tax, you may find yourself on the hook should you be audited.