On average, listings lease in the $20's per square foot per year. The Myrtle Beach submarket is going through a a boost in rates. In the last 3 months, the median rate increased $29 per sqft per year.
In the last 90 days, 8 listings have been listed, which means new listings are probably going fast. You'll want to be prepared to tour spaces as quick as possible. About 100% of the available leases in the Myrtle Beach are subleases, so you might be able to snag a great spot on a short term. 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 2,100 sqft. Most buildings in this area are close to 2 stories. Most buildings in this market were built in 1997 and are Class A.