Hi Jeff,
Buffalograss will work in Denver - but needs pretty much full-sun all day (a little afternoon shade is OK). 
Buffalograss sod isn't grown much in Colorado, because there isn't much demand and it's expensive to grow and harvest. The only grower that I know of in Colorado right now is Graff Turf Farms in Fort Morgan, which will make it expensive due to long distance freight. Check with them on pricing and availability:
https://graffsturf.com/

Another option for buffalograss is to plant it using plugs. You can buy plugs here and read about planting, etc.
https://toddvalleyfarms.com/legacy-buffalograss.html

I've also attached a couple of fact sheets on buffalograss and native grass lawns that you might find helpful.
Let me know if you have any questions after looking over this information.

Thanks,
tony