The typical asking rate per listing is in the $30's per square foot per year. The Myrtle Beach region is going through a an increase in rates. In the last 3 months, the median rate went up $13 per sqft per year. That's a 63% increase in rent.
In the last 90 days, 8 listings have been posted online, which means leases most likley are going fast. You'll want to be prepared to make an offer immediately. About 13% of the office spaces in the Myrtle Beach are subleases, so you might be able to find a shorter term or below market rent. 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 2,300 sqft. Most buildings in this market are close to 2 stories. Most buildings in this market were built in 1996 and are Class A.