Check out yachtworld.com
I would agree that a road trip to Annapolis would be worth the drive if you found a suitable boat. I would look for something in the 30-34ft range for single handed as a guideline. The older the boat you buy, the larger the size you may be able to afford. But don't forget, each additional foot of boat length is exponentially more expensive to maintain since we are dealing with volume, not a linear function.
I would also strongly suggest you buy a brand name that is still being sold today if you plan to resell and actually find a buyer a couple years down the road. For example, I've seen a Columbia Constellation on yachtworld that is in great shape for the age, but one would be hard pressed finding a buyer for a boat that has stopped being manufactured several years ago.
The article arhieve on Sailnet is a great place to narrow your search. Browse articles by Topic, then read through Buying a Boat articles.