A decent pop tester is going to run $500 - $1,500 used. Look hard at semi truck parts handlers, auctions, etc. You can find them. Most fuel injection shops can build lines and adapters to make the tester hook up to anything.
I second the comment on their usefullness. They will not always root out a bad injector, and are not the end all to test injectors. I have been frustrated with my truck because it displays symptoms of a bad injector with a slight miss, but can't find it. I'm living with it until the day I can afford 370's. Also had my pump balanced on the bench, it was perfect, no problem.