Hi !
Last fall, I purchased a 26' sailboat in good condition (only minor repair and maintenance to do) including a matching trailer and a 25 HP outboad engine for... 5000$. This is enough to get started, a licence for inland lakes sailing costs next to nothing to obtain and is not any tougher than a moped driver licence. I started by being used to smaller sailboats. I wanted something bigger for week-end getaways. In a few years, I may rent a bigger one for coastal or offshore sailing. The best book I read in the topic is Don Casey's "This Old Boat", which applies to just any size of sailboat purchase and maintenance. For getting into the terms and general business, "Sailing for dummies" is quite fun to start with.
If it is your type of dream, I would start by checking on the
http://www.trailersailor.com/ forum, which is focusing on affordable sailing. The key to affordable sailing is a swing keel sailboat you can put in and out of the water with a standard pickup truck, (without a crane) and keep into your backyard for self maintenance off season. On 22 feet sailboats or smaller, you often don't need to pay for mooring or marina fees. You simply bring it back home.
If you dream is more to learn to sail down to the tropics,
http://www.cruisersforum.com/forums/index.php is a good place to sneak into, but keep in mind such dream requires experience and training and a very deep pocket ! Purchase and maintenance cost of such sailboat is safe and affordable if you RENT (including skipper) offering to be part of the crew. Generally speaking, safe coastal and offshore sailing requires something like a rugged and top shape a 38-45 feet long sailboat. Such beast requires a crane and marina, special maintenance. Nobody will rent you such a sailboat if you don't have internationally recognized skipper certificates. This is a long but not outragiously expensive process. Even if you wanted to buy one, the insurance company will make sure only qualified skippers will be on the wheel, or otherwise will refuse insurance which will often mean you can't finance it. There are also US CoastGuards regulations to follow.
I hope this is giving you clues on how to get started into sailing.