Recently I have become interested in spatial effects on house prices (how where you are in town affects your house value).  I haven't quite gotten to the spatial elements yet but I was able to run a quick analysis on house prices vs. square footage, bedrooms, bathrooms, and acres.  Data was taken on 11-1-2009 and includes the vast majority of MLS listings for Bozeman at that time.  I made a calculator based on the regression that can be found 
here.  
n=931
|  | Price | Sq. Foot | Bedrooms | Bathrooms | Acres | 
| Min. | 19,900 | 437 | 1 | 1 | 0 | 
| Median | $329,900 | 2,214 | 3 | 3 | 0 | 
| Mean | $530,991 | 2,676 | 3.373 | 2.84 | 3.086 | 
| Max | $10,950,000 | 16,428 | 9 | 9 | 185 |  |  | 
**Update 11-6-2009:  The predictive algorithm has been much improved.  I also added an option for Belgrade homes on the calculator which can be found here.