Dave,
I say do it !!!!! As stated Factory Five has very nice Kits, and they have just added a more complete kit that just need Engine/Transmission, Wheels/Tires, paint and fuel pump to complete the car. Building there spec racer challenge series could be profitable as well. The Superformance cars are more complete, but are on the higher end of the spectrum but very nice as well. I am looking at my next project, and I am pretty much sold on the Factory five ( First, I have to finish the Z !!). Create your niche, and the requests will come. By the way, if all goes well my project will be a "bowtie Cobra". Good Luck