Lowes has a set that measure in English and Metric, in a case with an extra battery for about $30. These are electronic and therefor easy to read< the old verniers that I have are hard to read, old eyes, I also have a dial type which are easy to see. These were probably made in China and are accurate enough for what I do.
Midway has the Frankfort Arsenal digital model on sale for about $13; regularly over $20. With shipping you are back at the original price. Work well and had mine calibrated by QA at work and have been well worth the money.
+1 on the Frankford Arsenal digital ones from Midway for 12.99, although you need to have something else in mind to order, otherwise, the shipping will eat you up. If you are new to reloading and don't have it already, they have the Lyman's 49th Reloading manual for $19.99 - just got my new one in today from them! I seriously doubt that you will find it any cheaper anywhere else. Now if I can only get a commission for giving them all of this good press...
I have been using a set of RCBS plastic dial calipers for about 25 years. They still work fine for the precision I need. W/in a thou or two for case length is plenty good. The gun will not really notice the difference.