On average, listings lease in the $20's per square foot per year. The Boulder submarket is going through a a rise in rates. In the last 3 months, the median rate rose $28 per sqft per year.
In the last 90 days, 239 listings have been listed, so you'll want to check back regularly for new listings. About 42% of the office spaces in the Boulder are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,000 sqft. Most properties in this market are around 2 floors. Most buildings in this region were built in 1983 and are Class A.