It's definitely all about what an individual wants to do in a build versus buy scenario.
Personally, I think far too many who say they are going to "build my own", thinking they are going to save a bunch of money, greatly under estimate the cost of materials/components/parts, and far over estimate their fabrication skills, and buy the time they realize they are XXXX dollars into it, end up doing what's mentioned above.... spend more time tinkering and trying to adjust, then they do using/grinding on the machine.
In my experience, most just get frustrated, and then buy a "so-so" grinder. Get angry/frustrated again, then buy something they think is "better", and the cycle goes on until they finally break down and buy a top end grinder. The sad part is by the time most reach that point, they've already spent enough money to purchase 2 or 3 top end grinders, on machines that have zero resale value.
Two of the biggest reasons you pay the kind of money you do for a top end grinder is because of build quality, and the fact someone else has spent the time and effort to design/build in the necessary precision. And something not many consider.... resale value. Buy cheap, and there simply isn't any resale value, But, buy a top end machine, and in 10 (or more) years, if you decide you want to sell it, you get very close, if not more then you paid for it. Just last year I sold an old Wilton Square Wheel grinder, WITHOUT a motor, for $900. When I purchased it new, in 1988, I paid $550 including shipping.....just sayin.