Well I did a lot of checking into it (online) when mine got really really bad. The squeak is just one symptom of a larger problem. Sometimes oiling that particular gear (the quick fix) can be cheaper, but might not fix the other problems tied to it. Namely, your shutter timing starts slipping. To me, if the shutter doesn't work like it should (that's 1/2 your main control!!) it's a problem that should be fixed.
Good news is it'll last another 20 years after you invest $150.
P.S. However if you can't afford the CLA, it will work just fine. My squak started getting really bad after 5 years, and I shot on another 5 not knowing/realizing this was abnormal. Then again, I'm not sure if it is the cause of some yellow tints on some of my photos now that I think about it. If your pics look fine and you don't have the dough, you can put it off.
I did find it VERY hard to be inconspicuous at one law school event I was asked to take pictures for. Every time it squealed eyes darted over to me, and the room wasn't all that full. Makes folks self-concious if you're doing people-shots.