Great question,Jim. Although I typically encourage my listing clients or sellers to educate themselves and obtain as much knowledge about their home through inspections and appraisals prior to placing a home on the market, obtaining a termite clearance letter or purchasing a termite protection policy is completely optional and your choice.
Until recently, Sellers were required to pay for and deliver to the buyer at closing a termite clearance letter. Some pest control companies would not issue said letter unless you treated the home and purchased a termite policy (typically ranging from several hundred up to a couple of thousand dollars). As Joshua pointed out, there are still reputable companies out there that will conduct an honest inspection and furnish you with a letter for a reasonable charge, if you so choose.
The Georgia Association of Realtors 2007 Purchase and Sale Agreement implemented numerous new changes, one of which included placing the requirement for obtaining a termite clearance letter onto the shoulders of the Buyer (not the Seller). Further changes for 2008 place even more responsibilites on the buyer to perform their "Due Diligence" or accept the property "As-is" including all faults, repairs and potentially issues related to termites or other wood destroying organisms.
Because of the age of your home, voluntarily conducting home & termite inspections and making such results available to prospective buyers could give you an added-value edge on your nearby competition. Buyers will likely appreciate it because you are sharing important information with them, saving them money, and, by doing so, they be more comfortable and willing to make an offer and enter into a contract to purchase. Best wishes with your sale and next purchase - Ted