Not sure on building costs, but building new, good quality, I've heard about $100/ sq. foot. I don't have any stats to back that up, so take it with a grain of salt.
As far as the market goes, Pocatello has so far been mostly immune to slow down. Here are some stats...
In 2006, January through October, there were 1,003 homes sold, an average home price of $142,767, and 89 days was the average homes stayed on the market until sold.
In 2007, January through October, there were 1,022 homes sold, an average home price of $152,058, and a 99 day average.
You may also find some good informations posted from articles comparing East Idaho and Boise housing markets in this thread, page 3 (link should take you there).
http://www.city-data.com/forum/idaho...lo-area-3.html
Hope this helps,
Ben