I originally started in the new construction business by building a kit home, about 25 years ago. That was back when there were outfits that sold the kit and held the construction loan. BTW, the kits were low quality and short of just about anything that mattered, and the company made a fortune on overpricing and financing. Their demise gave me warm fuzzies.
Now, I would think your two biggest obstacles are going to be cash and codes. If you have your cash pile bulked up to the point that you can write checks as you go, congratulations, you have done well. If you need a bank to do a construction loan, good luck. I can't make a blanket statement, but I know from talking to my go to money folks, the days of financing owner-builders are largely over. As for the code mess, it's a very local thing. I can build a place in one township and have three months of hell with a code inspector that is a total prick, and sees imaginary violations. In another location, the inspector is totally clueless and walks around with a clipboard, and a slightly dazed look in her eye.
If you have what it takes, skills, time and money wise, go for it. Regarding your percentage of savings. I typically do all the mechanical trades on my homes, and the tile work and decks. I walk away with roughly 30% of the sale on a typical transaction.
good luck