I am with Jim. Producing kits is a giant loser unless you are talking thousands with an assembly line. I tried a "kit" Vanderbilt tender - ten dollars worth of brass, two hours of labor cutting, drilling, and packaging. I made three, and kept one.
The offer I made was "build it and critique it, or return it, or send me $75". I thought that was fair. That was when $75 bought more than one tank of gas.
If you have the bucks to get Malcolm to assemble a kit, then you have the bucks to have him make it from scratch. I get the feeling that assembly is about 80% of his workload. I don't build in plastic, so that is unfounded opinion.