If I understand correctly, the Menard's homes aren't really a kit. It's a set of plans, plus a materials list, i.e. take-off. The plans and take-off are inexpensive ($100 or so?). You can then take the take-off to Menard's (or anyone else) and buy your materials, at whatever price they will cost you. The price that Menard's shows you (let's say $70K) is simply their current estimate of what someone, somewhere, might pay for the materials on the takeoff. If you want something slightly different, or if your AHJ requires something different, you will buy those things instead of what's in the plans.
The person who builds the house needs to be able to take construction drawings and a pile of materials, and build a house, using the same knowledge and skills that would be used by anyone else building a house. There's no Lego-style, or (showing my age) Lincoln-Log-style easier way to do it, at least not with the Menard's plans.
That's my understanding, anyway. I'd get into Menards and talk with them. If this is accurate, then your prospect should go ahead and buy the plans with takeoff ($100?) and give them to you for you to quote the job.
Let us know what happens. I'm curious.
