Careful buying used measuring tools. It doesn't take much to screw them up. For value I have found these to be good...
http://www.jlindustrial.com/Precision_Measuring/Fowler/Micrometers/3761/4294966439/4294942759.html
Don't mind the retail price...never..ever buy measuring tools retail. If they aren't on sale today they will be tomorrow. Normally half or more off