When you get unfinished wood that has. Microbevel done and they say final sanding needs to be done on site. Usually that means it either needs to be screened or with a buffer use a piece of 100grit paper. The microbevel makes it so you wont have jagged edges but your subfloor needs to be flat. Any humps wont be fixed by the microbevel.

Depending on your location having a pro come out to sand could range anywhere from 2 to 5 bucks a sq.

It is new construction, but that does not mean the floor is flat. The builder has encouraged me to use prefinished. He said the finish is $2/ft. So my options are pre sand and finish myself or no pre sand and it done for me. The unfinished plank is much nicer than pre finished strip.