Although application prices usually range from $50-100, you still should apply to six schools. Applying to just one or two schools is much too risky. Applying to more colleges gives you a better chance of being accepted somewhere, and may give you options. The cost is well worth it.
You should apply to two schools that you think are a little above your level. These schools should be ones that usually accept people with a higher GPA or SAT score than you have. It is really worth a shot to apply to "reach schools" because a lot of times, there is something about your application that is attractive to them. If you played the tuba faithfully all through highschool, and the college you are applying to just lost the only tuba player in their marching band, you have a good chance of fitting nicely into that niche.
Also, apply to two schools that could really go either way. You think you could get in, and you want to get in, but you aren't completely sure. You have as good of a chance as any.
Lastly, make sure to apply to two schools that you can certainly get in. Applying to "safety schools" is really important in case your other four fall through, you will still have a place to go come September. You can always transfer if you feel these schools aren't challenging you enough.