There is always a market for hand made items. However getting back your time and material costs are another matter. As a pricing guide I would search out and see if anyone else is doing it and see what their prices are.
Usually Tamiya kits are well engineered and everything fits properly especially the larger scales. I would re-check everything leading up to that step. Sorry I couldn't help much.
Just want to add more praise for Steve Kohler. First rate service including a phone call to me to describe everything in exact detail. I had the kit in 3 days from his place to Georgia