How hard is it to sonically clean injectors? - We've got sonicators at work, but they've generally got water in them rather than solvent (and I suspect you can't clean injectors with water).
If it's as simple as sitting them in a beaker of solvent like acetone (because that's a really good solvent - it's dipolar and aprotic) and leaving it for half an hour, you could probably do that at home with one of those jewlery cleaners you see in various catalogs.
I know the professionals will say you need to flow-test etc, but if you're confident they're working and just want to clean them, would that work?
If you were inclined you could pulse them with a 12V source so that they open and close.