I pay $30 a month (includes a $6 tip) to have my hair cut. I schedule next month's on the way out of my current cut. Around $1 a day for hair I'm happy with is a good price IMO.
The only person I've found who I trust not to butcher my hair costs $90 after 20% tip, so I get mine cut as infrequently as possible. Usually about 6 weeks.
10 days seems to be the exact amount of time it takes before my hair needs to be cut. I actually cut mine every 7 days due to my schedule. Its either every 7 days or 14 days and I get annoyed as hell by my hair growing out by the time 2 weeks approaches.
I'm going to start doing the expensive place every other time and maybe fit in more cheaper places inbetween and then have the expensive place set the style again.