Hey guys,
Just thought I'd chime in here. I have a little bit of expierience with precision tools. (I'm a 15 year tool and die maker) Buying the cheap $10 -$40 calipers is just asking to buy it again, and again,and again. there is a reason that auto mechanics buy snap-on, matco, mac, craftsmen tools instead of harbor freight and other cheap tool stores. they rely on there tools to last and perform. precision tools are no exception. Starrett, mitutoyo, brown and sharp, fowler ect. cost more for a reason. THERE WORTH MORE! When your using a tool to make a living, ( or even just pad your income

) it has to perform. I personally have about 15 grand into precision measuring tools (mostly starrett) alone. you wont find a single harbor freight tool in my box, because you can't trust it. I deal in tolerances of +-.0002 all the time, and couldn't trust the cheapy tools for that. As far as accuracy goes, the same starrett, vernier, dial, digital caliper is just as accurate as each other. ease of use is the big difference. old timers seem to like verniers, (probably cause thats what they learned on) I like dial myself. The young kids up and coming seem to like digital. (fast and simple) But they will do the same job, with the same results. So, personally I like the idea of "buy a tool for a lifetime, not just for today". To the OP, if $40-$50 is all you can spend, pawn shops are another goldmine for good tools. And they usually have a set of gauge blocks so you can check the tool out as well. A used ugly 40 year old starrett will beat out a china harbor freight crap any day.
Just my .02 minus taxes
,Tom