Hi Mike, I don't know about cheap upgrades but saw on Cloudy Nights a simple way to give better control on a focusser. User had fitted a long arm, 100 -150mm maybe to the knob so he had better control over smaller movements. It might possibly also give better leverage against snugged focussers where they have been tightened to prevent slippage.
You wanted cheap ...
I might have a go at making a lock-on arm and see how it works for myself. My little 80 F5 can be a bit pernicketty on that sharp point. Some method of releasing to make coarse adjustments then a knob to tighten it on and use the extended arm to finalise the focus.
Hmmm, .. another wee project to play with. Like I haven't got enough already.
Huh ! 700 posts already ... how about that ?