PH meter

Milwaukee MW-101 is a decent meter with just enough features and precision for brewing usage.  You do want a meter that reads down to the hundreth of a pH unit, even though you will only need to know down to about the tenth of a unit.  It does incorporate a manual temperature compensation feature, but its not really needed.  Automatic temperature compensation is not needed.

The meter is under $80, but do get some small bottles of pH 4, pH 7, and storage solution to help protect and verify your investment.