Since you've got the injectors out already, you should condsider making a pop tester out of a grease gun. Check out
this thread, from about post #18 down for instructions on how to make one out of a grease gun. Its really easy and relatively cheap to do(less than $50). If you buy injectors, you're gambling that they will open at the right pressure and have the proper spray pattern. Don't be discouraged from used ones, though. Even new Bosch injectors right out of the box are bad more often than they should be. Being able to test and adjust your injectors is very satisfying and suprisingly easy.