I have a Mitutoyo (which thank you for this thread as I found that I had left it on for weeks when I looked for it to get the spelling) and a Harbor Freight Inchman.
While the Inchman currently has a dead battery, I don't recall it being subject to battery drain whilst turned "off".... unless I forgot to turn it off, it has given me as
about as good service as the much more expensive Mitutoyo. I haven't tried to benchmark the accuracy of either but they both seem to meet my needs.
I was just thinking about the subject this Monday while I was poking around in the Notions section of a Quilt Store.... sometimes there are tools there that can be used for modeling.
I was surprised to see a handheld digital calculator custom designed for quilters.... with buttons and functions to calculate yardage yields for standard width fabrics and other calcualtions that I did not note. Now, Quilting is probably a couple of orders of magnitude larger than Model Railroading, but it seems to me that it wouldn't take anything beyond changing the software a digital caliper to get 1/48, 1/64, 1/87.1, 1/160, or 1/220 readouts.... possibly the English/Metric button could be used to double up so that at least O/S and HO/N versions could be made economically. With Harbor Freight selling them for under $10 at retail it would probably be realistic to be able to buy one for less than $40..... depending on the markup the importer would need. I have no idea if any of the OEM factories in China would consider doing such units but it certainly would be a handy tool.... perhaps not for precision pattern making, but good enough for general modeling and use on the layout....
Charlie Vlk