About 20 yrs ago I bought a Bridgeport with a veri drive head a vise and a Mitutoyo Digital Read out for 3500. Had power feed on X axis. They are extremely versatile machines, they still have their short comings. Still all and all the biggest limitation has been my own lack of creativity. Tooling is very common and can be purchased as you need it for reasonable prices. My Bridgeport with tooling and still in very nice condition would fetch about 5500 in my area. All that said, worn lead screws, which affects accuracy can be dealt with with a Digital Read Out and good machining techniques, like using conventional milling, not climb cutting. If you want to climb cut, you can lightly clamp down on the motion of the table with the table lock....but this discussion is probably a little premature.
How do you propose to get it into the basement?
I also would encourage you to talk to dealers that are close to you. You will learn a lot. Usually they have a shop where they repair machines and they can tell you what to look for in terms of wear, and general condition. There are some nice threads and photos on Practical Machinist website about Bridgeports and clones and inspecting for wear and condition.
Tim