$30 an hour for getting yourself out to the gig and capturing the waves should be reasonable IMO. That's the real pain in the butt. You have to put up with drunks, put your gear in a toxic bar environment, wrangle with routing/cabling/the house PA/etc and transport the gear back and forth.
 
Mixing? IDK... if they were demanding the finished product ASAP I personally would charge more than if I were allowed to poke away at it casually. If I could do it within my own timeline and they weren't super finicky (minor adjustments... not total mix overhauls) or insist they come by all the time and involve themselves in the process (I do not like people hanging around) I'd probably just give them a flat rate of like $100 or less for an albums worth of stereo waves at pre master levels and another set that I "mastered" myself for immediate consumption.
 
If they WERE going to crawl up my butt during mixing/editing I'd probably charge $15-20 (seems like reasonable semi pro demo rates) or more likely tell them to find someone else if they were particularly annoying.
 
I however probably won't attract very many clients for quite some time and frankly I'm okay with that. I have my own music to make.
 
/not a pro

So many of these things to some degree have happened, so this reading is enjoyable! The word of mouth (or of ear!) has happened in this case, since the one who contacted me about this new demo CD was the fill in drummer of my friend's group I recorded a few times before - more of less for some "tips" and drinks. His drum track came out particularly good on that one, the way I mic'd it, so I think that helped convince him to get with me again. I love the stuff Beepster wrote about putting up with all the stuff and annoyances of a bar-scene recording ! That is another story...of how my little spot to place my interface/laptop on a "chair" was too close to a coin operated punching bag, with some very drunk guys who half the time were missing the bag, and stumbling over bumping into me.......... 

Yikes. Yeah I don't like those punching games. Seems like a bad idea when alcohol is involved and when I see them in a bar I know to watch out for meatheads. I miss playing live but I don't miss the ruckus. Guess I got old.
 
Glad you and your gear made it out undamaged. Might want to rent a snake or something for next time so you can get yourself set up in a less chaotic part of the bar. Cheers.