I usually agree with Stan, but using a bench grinder for a buffer is not a good idea. The main reason is that the buffs are far too close to the motor housing. This will eventually make you tilt a blade out a bit and it will snag. Knife buffers should have long shafts with lots of clearance. The HF long shaft buffers aren't much, but are probably the cheapest available. Use a 6" buff on them if an 8" buff bogs down.
But, a novice does not need a buffer...and should avoid one.
No, a router controller won't work.
I hate to give buffer advice, because I don't like untrained people using them.....but........The cheap way to get a slow speed buffer and good clearance is to use a 18-24" long, 1" mandrel shaft with bearings and a pulley. Run it with a 3/4HP motor, and turn the shaft at 1200 RPM. After you get more buffing skill, you can change the drive pulley to make it run at 1500-1700RPM if you think you need the speed. make the whole thing rock solid and totally rigid. The last thing you want is a shaky buffer.
Now, about the cost of a dedicated 1750 or lower RPM buffing machine, it is money well spent. This isn't a place to pinch pennies.
