Garage quoted me new injectors, should I get a second opinion?

[dominictoretto]

Took my Grand Cherokee in for a rough idle and the garage jumped straight to quoting me for four new injectors, which felt like a big leap from a twenty minute look. I've only had the car about a year and I'm not sure it actually needs replacement rather than a clean. Someone mentioned there's a Jeep injector cleaning specialist in MBZ City who actually diagnoses properly instead of guessing, and I'm thinking a second opinion is sensible before I commit to that kind of money. Has anyone been quoted for replacements and then found out a clean was all it needed? I don't want to be that person who ignores good advice and ends up paying twice, but I also don't like the idea of throwing parts at a problem. How do you even tell the difference between a clogged injector and a failing one?