Hope you have a good knowledge of woodworking and metalworking. There are a few suppliers of parts, Novak and a lot more but if all you are going to make is 4.25" scopes, there will quickly come a time when everybody in your area has one and wants to make something bigger. ASM has a truss tube DOB kit starting at 10" ($850) and up to 24".
For the most part, it`s more of a gathering of parts from here and there and do some work and put it together.
FWIW, Stargazer Steve does have a nice kit for up to a 6" scope but they are a few hours to assemble and paint and that`s it. You really do want to keep the people there for as long as possible (within reasonable limits, of course) as what they are doing is a hobby work rather than a workplace assembly. Invariably, somebody is going to want to grind a mirror so be prepared for that.