Unless you're planning to buy a new Sunfish or Laser, chances are your "under $2,500" small sailboat will be a used one.
There are literally hundreds of small, inexpensive used sailboats on the market all across the U.S. In my "resources" section, I have listed Internet links to several websites where you can search for used sailboats. Most of the websites for sailboat owners have listings of boats for sale, as well as lots of fascinating information about the boats, repair issues, how to improve performance, and social events for members.
What are the top candidates for "sailing on a budget"? This is my personal list. It should get you pointed in the right direction. In the Resources section on this page, I list several owners associations and sailboat companies where you can find more detailed information.
O'Day Daysailor - This is the boat that I own and I love it! (Can you tell???) There are several versions of the daysailer, but they are all 16'9" long and 6'3" wide. They are easy to sail, fit nicely on a trailer, and can really take off in a strong wind. Perhaps I am just lucky, but I find this boat very stable. I have yet to capsize!
O'Day Mariner -- The Mariner is about a foot longer than its Daysailer sister and is 7' wide. Below you can find a short video of a Mariner sailing.
MacGregor Weekender 21 -- This is a small, trailerable boat with a big feel. It has a cabin that can sleep up to four people and is known as a very stable ship.
Com-Pac 16/19 Daysailer -- I seriously considered buying a Com-Pac before eventually purchasing the O'Day Daysailer. Com-Pacs are classic-looking boats that have endured very well over several decades. They are still in production.
Catalina 22 Pop-Top -- Catalinas are like the Chevrolets of the sailing crowd. Although newer and larger ships can cost more than your house, there is a plentiful supply of sea-worthy older boats that are on the used boat market. The Catalina 22 in various configurations is one of the most popular. The "pop-top" means that the "ceiling" or top for the enclosed cabin can be pushed up to provide more headroom down below.
Catalina Capri 14.2 -- At just over 14', the Capri is somewhat smaller than the other daysailer boats featured here. It is a good choice, however, for someone who does not need a cabin and who wants to buy something a little newer. If you're interested in sailboat racing, there are numerous fleets of boats around the country that organize races for this class of boat.
Hunter 25 Daysailer -- The Hunter is a bit larger and more expensive than most of the boats listed here, but you can find older sailboats that will fit your budget. At 25' long they are trailerable boats with large cabins. There are several other smaller Hunter sailboats that are worth researching online such as the Hunter 22.
West Wight Potter 15 -- I love just looking at Potters! They are a little ungainly in design, sit high in the water, and probably remind some people (me) of a floating bathtub with sails. But take another look and they might even seem cute! They are incredibly practical boats and offer a great deal of space and sailing fun for their size. It even has a small cabin below. Potter also makes a larger model, the Potter 19.