I build for a lot of reasons, I love the feeling when I finish the rod, admiring its beauty, looking forward to fishing it. Also very important to me is that I can fish the best rods in the world for about half the cost of what it would cost to buy the name brand hi mod rod. But I agree with DVT, if saving $$ is your ONLY reason to get into building, it's not a good idea.
I think I keep building spin rods, even when I don't need another, is that I have developed a "signature" design that really works, and no factory company offers anything close to it.
I also have built a bunch of rods for an educational foundation auction. Nice to support local education with my skills, and neat to see what others will pay for one of my rods. Many builders are building rods for kids and rods for vets, both admirable endeavors.
I built my first rod when I was a teen, parts from Herters, "Finest Procurable Quality," built a fly rod during college finals week one year when I was well scholastically prepared, fished it before taking my last final. I have many fine memories from rod building. It is a neat hobby, even if you don't get into selling. Especially if you don't get into selling (warranty issues, broken rods, "that's not what I meant by MH") My family and a few close friends value their rods from "Custom Fishing Rods - MJ Danek" That's what the label says.