Yep, the crux is always that, subjective value... eh?
It appears that some PJs benefit "more" than others. Or what I mean to say is that certain PJs can be made to be closer to "accurate" w/o pro cal than some others. You will have to research owner threads of the PJ you own.
So with the above in mind, I didn't get a pro cal. The bulb dies/changes at a fast enough rate that the accurate calibration may not even stick that long. And I only watch movies. If you are gaming, tv watching, computer-ing, etc, then I think it would be even less worth it.
Im at about 200 hours now, and have been trying to retrieve a calibration disc from my friend. Some people recalibrate every 200 hours. I don't think I'll go quite that far, but it won't be very long either before I re-do it.
I sometimes think that its more worth it for typical TV's since the color doesn't change as fast with them.
oh, btw, I've read that just because someone is certified does not mean he is a worthy calibrator. You might be able to research local trusted persons, with some luck.