On average, listings lease in the $10's per square foot per year. The Galveston region is seeing a decrease in rates. In the last 3 months, the median rate decreased $6 per sqft per year. That's a 24% decline in rent.
Compared to the rest of the Houston Metro market, the Galveston submarket has lower rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 29 listings have come on the market, which means new availabilities most likley are going fast. You'll want to be prepared to make an offer immediately. 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 1,300 sqft. Most properties in this market are around 2 stories. Most buildings in this area were built in 1973 and are Class B.