I suspect, but don't know for a fact, that rebuilding a rusted junker is more of a project than building a kit or semi-kit car. Whatever.
Here's something to consider, though. When I was looking for Jag E-Types, the #1 Jaguar in the country (from all of the concourse shows that year) was for sale for $18,500. That was a lot of money at that time. I bought the rust bucket for $5000, and put about $12,000 into parts and materials, and over 2,000 hours of my time. If I'd gotten a part time job at McDonalds, I could have taken out a loan for the #1 car and paid it off in a couple of years.
My point is to ask if you want the car or if you want the experience of building one. Two different things. When I sold the Jag, I felt no emotions, as it was the accomplishment I wanted, and not so much the car at that point.