The thing I like about DIY stuff is that if it breaks, I can fix it very fast for practically nothing. Also I have no qualms about modifying the stuff I build if I think of an improvement. I'm not so fast to take a hacksaw to a commercially built unit because if I wreck it, I may not be able to fix it because I couldn't get the parts.

As an example, I built my own telescope as well, a 15" dob. I know others who have bought basically exactly the same thing, but they're terrified of making the slightest scratch on their scopes, whereas if I think of a new way to try venting the mirror box, I have no problems with breaking out a big old hole saw and opening a few new holes in the sides. Because I know that even if I screw it up completely, I can build a new mirror box for about $30 in an evening.

In general (with telescopes anyway), the people who "just buy" wind up with nicer looking stuff, and the people who DIY wind up with stuff that works better or is more practical.