what I charge by the song may not be competitive in your area, so I'm hesitant to say. And I don't own or run a studio...My "studio" is pretty much a mixing suite in my house (treated/isolated room in my home used for mixing and mastering ONLY), and I track at the band's designated area of choice - usually their practice space. My rate per song varies depending on what I do (record/mix/master, just mix, just master, etc.). Going by estimates I've done with past projects, my per song charge equals to between 10 to 20 bucks an hour...if it's a really unprepared band and they do just a couple songs, that's where I make less...If it's a decent to good band and they do more than, say, 5, then the outcome of the per song rate equals more per hour because I've spent less time cleaning up the mess, and most of the settings and start point of the mix transfer to all the songs from the session (i.e. the time to get the right mix is ROUGHLY the same for 1 song as it is 5 in most cases).
example...Say I record a ROUGH band for 1 song at 200 bucks for the song.
10 hours tracking for the whole band
4 hours editing
4 hours mixing
2 hours mastering
_______
20 hours total @200 bucks = 10 bucks/hr
good band with 5 songs at 150 per song (multi song discount) = 750 for the project
18 hours tracking
4 hours editing
10 hours mixing
2 hours mastering
_______
34 hours total divided by 750 = 22 bucks an hour
these figures are arbitrary, but are close to what I do and how it works out.
Due to the limitations I have in terms of a studio, I push for bands to track elsewhere and give me the files to mix and master...I tend to make more off those projects charging about HALF as much as I do for a full track/mix/master job because truly the hardest part (tracking) has been done. I have a freelance position in a real studio available to me, but I must bring the clients there myself...with the studio comes an hourly rate, so guess what bands choose? Record at practice spot, have me mix at home....sucks.