Explorer, here are ones that I recall specifically enough to write down here.
Kentucky
I-65 Exit 53. Just west of the exit there are gift/souvenir shops on the left (south) side that sell paddles. Last time I checked, more than a few.
I-75 Exit 41. From the exit turn to the west, and then immediately left into a long shopping "barn" called the Dogpatch something or other. The building is tucked into the southwest corner of the exit, so you can't miss it. The paddles here are a bit sterner than the usual souvenir shop items, and I recall them being around for real use when I was a kid (never had one used on me, though
).
Georgia
On I-75 between Valdosta and Macon is an exit/rest stop called "Southern Plantation." Quite a large sign advertises it. Paddles are to be found here.
I know of others, but not on the main drags or not well enough to give directions to without some work.