Depends on what track you go to, and where you want to sit. A friend flew down last year to attend the Coca Cola 600 with me - one of the biggest races of the year, as it is the longest - because my husband was part of an Army detail that received coins from one of the Chiefs of Staff or something. Anyway, since I also held a military ID card, I was able to get us seats for $35 apiece, right on Turn 2. We ended up in the infield though (long story). But I don't think I've ever paid more than $100 for a single ticket, probably not even that much.
If International Speedway Corp. gets their way, there will be a track in Washington state sometime in the future. Until then, there's a couple of tracks in California......Trust me, I was just as skeptical as you are when my husband said he wanted to take his father to a race for his birthday....but I kept an open mind, and I'm glad I did. Turns out, my very first race was the last one NASCAR held at that particular track, so I even got to witness a little bit of history - AND the driver I picked to be "my" driver came in second, in one THE closest finishes in NASCAR history! Granted, NASCAR isn't for everyone, I just wish more people would have an open mind about it.