Well, after doing some Intarweb searching, it looks like the cost per square foot ranges between $20 - $30, depending on the size and whether or not there's a bathroom going in. I'm guessing ours will range about $25 per square foot. We don't have a bathroom going in, but it's a relatively small area (< 200 sq. ft.). My guess is that we could get a real good job done for around $5,000.
As you can see, I'm leaning towards a contractor. I have a couple appointments with people this week. This is something I'd like to do myself, but the more I look into it, I just don't think I have the time or patience (I'm the kind of guy that, once something is in his head, wants it done yesterday).