I built this one, with a variables such as a 6" face 3000psi gauge, but the basic premise works, and it can be done inexpensively with a little patience.
How to build a diesel injector pop tester - Topic
I've done 3 sets of injectors with it. It takes a little use to get comfortable with setting the pressures, and a stout bench vice next to it makes the process a lot easier. The vincewaldon site is invaluable for getting into this process.