Most listings are in the $10's per square foot per year. The Centralia submarket is going through a an increase in rates. In the last 3 months, the median rate rose $16 per sqft per year.
In the last 90 days, 17 listings have come on the market, which means listings most likley are going fast. You'll want to be prepared to make an offer immediately. About 12% of the available leases in the Centralia 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 available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 610 sqft. Most properties in this market are close to 2 stories. Most buildings in this region were built in 1935 and are Class C.