For you guys that like Harbor Freight, try this out. Buy a cheap sander, and keep this on it permanently. I’ve had the same one on a cheap 20$ sander for 4 years now, never changed it.
https://duragrit.com/DuraDisc-Carbide-Sanding-Disc.html
Then keep whatever fine paper you normally use for finish sanding on your good Dewalt, Mikita, Bosch sander, and just switch between the two.
Also one of these is a must.
https://www.harborfreight.com/sanding-belt-cleaner-30766.html
Works on belt sanders, disc sanders, hell it even works on nail files. Quit wasting money on sandpaper. Spend that money on lumber, or spray lacquer, or beverages.