On average, listings lease in the $20's per square foot per year. The Castle Rock submarket is going through a a rise in rates. In the last 3 months, the median rate went up $28 per sqft per year.
Compared to the rest of the Denver Metro market, the Castle Rock region has lower rates, so you should have no trouble finding a great deal in this discounted region.
In the last 90 days, 18 listings have come on the market, which means new listings might be leasing quickly. You'll want to be prepared to make an offer immediately. About 33% of the listings in the Castle Rock are subleases, so you might be able to find a shorter term or below market rent. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
Even though the median size is 11,270 sqft, there are still 0 office spaces below 2,000 sqft. Most properties in this area are around 2 floors. Most buildings in this region were built in 1997 and are Class B.