I am not on a tight budget for this project $200 is not a problem for this one
I'm going to measure camshafts -> valvelift
It seems a bit strange that you are ruling out mechanical amplification, then, because it would have to be a pretty strange setup where that wasn't possible.
You're also asking for massively better resolution than would normally be required to measure valve lift, too. The valve clearance in a running engine goes all over the place and also varies with wear and so on. Do you actually need the resolution down to a fraction of a thou?
Having said all that, you could probably find a digital dial gauge around the sort of budget you're quoting and that would get you far better resolution than you're asking for.