Your best source is to contact a REALTOR that can keep you up to date. The market continues to be a moving target to the average "per square foot" sales price today may be vastly different from what it might be when you start looking. Also, the Pawleys Island area has so many different types of communities that a generalization of 3500 SQ FT may not give you a true picture of what you can expect a sales price would be in a home that you might be interested in. For example, a 3500 SQ FT home in a community like Prince George or Debordieu will be worlds apart from a 3500 SQ FT home in Litchfield Country Club. See what I mean? And ... you are right - the comparison tools that are our there on real estate websites like Trulia and others are a good starting point but don't give a true picture or the reference points that you need to really understand what is happening "on the ground" so to speak.
I have been in the business in Pawleys Island for 21 years and would be happy to help you if you would like! Good luck with your move from Birmingham. I am sure you will find Pawleys to be welcoming and a perfect place to call home!