First of all, there's not all that much money to be made in this business and anytime I can make something for myself, I certainly will. I started out learning to read vernier calipers. Then dial calipers came along. I was asked a while ago why I don't use digital calipers ? Well, the dials work just fine for me, the digitals aren't any more accurate or faster and I never have to replace the battery in the dial calipers. I do have a set of $15, 4" digital calipers that I intend to mount on my lathe compound to facilitate my ring-cutter advancement. I'm currently using a 1" dial indicator but my compound has 3 1/2" of travel. It will be $15 well spent.
A U.V. system can cost you a couple of grand or more, but why ? I use less than $100 of auto-clear in a year. When I can, I buy it on sale, by the gallon. In almost 20 years of building, I've never felt the need for a sanding mandrel either. Do your work well and your shafts fit.
I've to come to understand that it's not how much you make, it's about how much you have left at the end of the week. You can call me cheap if you want to but I'm running a business here. I wonder if Gus or DPK used DROs ? Not likely,......they didn't need them.