hoffa, the factory manual for my car actually says that if the special service tools aren't available, you can stick the injector in a jelly jar or mason jar and watch the spray pattern to see if it is even, then measure how much gasoline it shot in one minute to check the flow rate. And, that with fuel
vapors you can also blow yourself up very easily.
With diesel injectors the pressure should be much higher--there's a real risk on injecting diesel into your body. So if you don't want to screw around with jelly jars, there are special machines they put the injectors into ($$) which show flow rates & let you observe patterns safely. Then there's the cleaning and adjustment--if any is needed. I think the cheapest net price I ever saw was 20-odd dollars a piece, so $65 for at least two injectors is not unreasonable.
What would it cost you to buy two new injectors (assuming it is two you need) and then take your time screwing around with the two you have? If it works, you have a spare set that you can swap in right away if the running set clog or fail--and that's worth something too.
Running a cleaning solvent though them for any length of time assumes you have a PUMP
of some kind and can jerry-rig a jig to connect them to it, so you can flush them through. That's gotta cost something, surely you don't want to pump
cleaning solutions through the high pressure pump
and engine systems itself?