So I'm thinking of getting bass lessons. What are somethings I should look for in a teacher? Are the people who teach in music stores okay? What about people from craigslist? Does a more expensive teacher mean higher quality lessons?
Best thing to do is look around and ask for a single lesson to try it out until you find someone you click with. If you find a good teacher, you'll know they're a good teacher because you'll learn lots and be inspired.
Generally you would think a more expensive teacher would mean quality lessons.

In my opinion look at their qualifications. Have they studied a degree in music etc. How long have they been teaching and playing guitar?

I recently found my teacher 2 weeks ago for classical guitar. He's been playing classical for 12 years. As he opened the door one of my best friends from school who played 7 years answered the door and we shat bricks and shared lots of laughs then my teacher came behind him and it broke the ice a lot and yeahhhh. Turns it he is also my friends teacher and now they hang out. I got lucky and met an awesome teacher who he and i are both hell chill and relaxed around and i'm learning a lot with.

But yeah, i think qualifications are important. Thought i'd just share my story :P
A more expensive teacher is usually more egotistical and/or more specialized. Price doesn't mean a whole lot.

What does matter is what they know and how well they can communicate that information to you in a meaningful way. Do you and he work well together? That's important. If you don't like the guy, you won't be learning as well from him as you would from someone else. Is he really technically skilled? Is his technique good and tension free? Does he understand theory? Does he integrate it into his playing?

Of the utmost importance is knowing what you want to learn. I personally want to learn more theory and compositional techniques, so I would want to learn from someone who can teach me that rather than someone who specializes in jazz-fusion improv and technique.