What do you think of simply pricing gigs for...

$50/hour, two hour minimum
Each set = 45 minutes, 15 minute break between

I'd like to add mileage figure as well, but afraid it would run 'em off. But I don't know that. Mainly just curious if you think the $50/hour, two hour minimum seems like a good way to do it. Instead of saying "$150" or $100" or whatever.