Cheapie import DRO scales for a Mill/Drill Quill?

I've been contemplating upgrades to my Enco (Late 80's mfg, round column) Mill/Drill...
I plan to add CNC to the X and Y, and later to the Z.. the Z is going to take a lot of work on
the quill feed or building a new Z drive system...

Anyway... that's not the point of my post.. (damn antihistamines for allergies keep me
from thinking a straight line...).

I happened to spot some "cheapie" DRO scales on eBay in the $25 to $35 range, for a 4" or
6".
I was wondering if anyone had any experience with these glorified calipers with delusions
of grandeur on a Mill/Drill Quill?

In the short term, just as a "dumb" DRO...
And MAYBE, in the long term, could one be interfaced with a computer (paralell port) as
part of a CNC retrofit?

I'd appreciate anyone experience or views on 'em!
Paul F.