Most listings are in the $10's per square foot per year. The Lower Allen submarket is seeing a a rise in rates. In the last 3 months, the median rate went up $19 per sqft per year.
In the last 90 days, 4 listings have come on the market, which means listings most likley are leasing quickly. You'll want to be prepared to make an offer immediately. 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 1,500 sqft. Most buildings in this market were built in 1986 and are Class B.