The typical asking rate per listing is in the $10's per square foot per year. The Eureka region is going through a a rise in rates. In the last 3 months, the median rate went up $1 per sqft per year. That's a 4% rise in rent.
In the last 90 days, 10 listings have been made available, which means spaces are probably going fast. You'll want to be prepared to tour spaces as quick as possible. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 700 sqft. Most buildings in this market are around 2 floors. Most buildings in this market were built in 1948.