Hello

Hello. My question is how much would it cost (+/-) to repair the ignition timing, and the malfunction indicator light in a 1989 Nissan Sentra? I took my car for a smog check yesterday, but it did not pass. The emissions test, and the visual inspection passed; however, the functional test failed. I went to a garage to hopefully fix these problems. The owner ran a diagnostic test, and told me that with labor and parts it would cost $950.00. This is only for the ignition timing. Is that price a bit high? The kit that is used to replace the timing belt (chain) from an auto parts store only costs $120.00. That leaves $830.00 in labor. Is this too much?

I know that I have asked more than one question, but I really do need help from an auto professional who will give me an unbiased point of view.
Thank you,
Celeste