The way I would suggest is to ask people that you know, where the have gone and what they liked and didn't like about where they went. Then when you get a list of places, contact them to get more info.

Check out who mastered the records you love.

For example:

John Golden in Cali does as lot of Sub Pop's stuff, including the Shins.

Google him. Visit his website. Email his office. Mail him your stuff. And away you go.

This works with most mastering folk...as well as a lot of mixing folk, and just folk in general.

Email people, call people, be polite, ask questions. The people who make the records you love will often work with Indies for cheap...give it a shot! Good luck!

Thanks for the advice. I'd like to use someone local. Does anyone know a mastering facility in or near Dallas with a good reputation?

You might have a look at this link:
http://72.14.207.104/search?q=cache:Hg2ZJ_aI7WkJ:www.governor.state.tx.us/divisions/music/directory/studios/recordingstudios.htm+dallas+audio+mastering&hl=en

Seems to have a bunch there and you might find a place that you trust and like.

There are many online mastering services that let you prelisten the mastered tracks before deciding if you want them, so it's free. One of them is....ooops this is a real SPAM! me...

Correct Giovanni, it is spam. Don't make me edit posts.