I believe it was $3 to sit under the dryer for 5-10 minutes. Officially I think it's 5 minutes, but by the time they get to you, another 5 minutes has passed.
Overall, I think it's more cost effective to deep condition at home. Sometimes I would wash my hair at home, use deep condition and walk right into the salon with the deep conditioner on my head and have them rinse it out, use conditioner and the roller set my hair. I wasn't charged extra for it.