Oh yes, gosh, I almost forgot my office....
If you read the sales rules then you know about the non-profiteering rule/principle.
So, returning to your question, the fair price to retail this piece on RWI is how much you paid for it.
If you intend to charge your own labor as well then you need to also become a patron and sell in the collector's watch corner.
To sell in the first place on RWI you need to get certified (separately from subscribing for patron).