Some thoughts for logjam
First, let me congratulate you on what appears to be a well thought-out start in the hobbyist kit business.
Oh, I found out about your project at:
http://boingboing.net
I built an IMSAI 8080 back in 1976 when I was a teenager; it was a valuable learning experience and the unit worked for many years. I had hoped to get a modern IMSAI replacement, but it doesn't look like there's been much progress in that direction for the past couple of years. So I find myself looking at your efforts with significant interest.
I hope that you don't have any intellectual property issues from Ed Roberts or anyone else connected with MITS/Pertec. As long as the project is clearly marked as a replica, I guess there shouldn't be a problem.
Those of us who were active in the early days of S-100 machines recall that not all boards available back then worked well, or even worked at all. I thinking of the MITS 8 KB dynamic memory boards; these do not need to be resurrected, at least not without needed improvements.
Having used all of the early Altair models, the best one in my recollection was the 8800B that had the paddle switches instead of thin toggles. It also had a "slow" single step mode along with much better graphics on the front panel. If you were doing one of these, I'd likely be writing a check today.
The kit price seems a bit up there, but not overly so. Certainly it's better to have a deliverable kit at a high price than a less expensive model that never sees the marketplace.