Or just drive around the neighborhood you want and talk to the neighbors. Tell them you are looking to buy in this area and see if they know anyone thinking about selling. I'd also befriend the local hotshot realtors as they will know about stuff going on the MLS before it shows up to the general public.
Side note, but I have a 2nd beach home. After the "newness" wore off and realized it was a luxury we didn't need to use every weekend, we decided to turn it into a summer rental property and mainly treat it as an investment property these days, while using it for ourselves pre & post summer season. I don't want to derail the thread, but 2nd home ownership has it's complications. Had we not been able to rent it out, I'd probably have some buyer's remorse.