On average, listings lease in the $10's per square foot per year. The Galveston submarket is going through a an increase in rates. In the last 3 months, the median rate increased $1 per sqft per year. That's a 8% rise in rent.
Compared to the rest of the Houston Metro market, the Galveston region has smaller rates, so you should have no trouble finding a great deal in this discounted region.
In the last 90 days, 29 listings have been made available, which means listings are probably going fast. You'll want to be prepared to make an offer immediately. 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 1,300 sqft. Most properties in this region are approximately 2 floors. Most buildings in this region were built in 1973 and are Class B.