All depends on the price and condition of the bridge. If it is old and shows a lot of wear and tear it will probably need a complete overhaul, scraping, Blanchard grind on the table, new bearings and new gears. These items add up quickly in both dollars and time. A Taiwanese machine like a Precision Mathews or similar caliber supplier will yield a ready to break-in and run machine with a warranty and lots of modern features that were considered add-ons and were expensive luxuries when the Bridgy was new. So I would look closely at the Bridgeport and make sure you are not buying a headache and a future resentment for not going ahead and getting a new machine to begin with. A lot also depends on exactly what you plan to do with the mill once you have it n your shop. Unless you are one of those extremely lucky few who can afford to buy one, just to have around in case something comes along or you get involved in a project of some kind. The best places I have found for used Bridgeports and machining equipment in general are old High School shop class machines they are getting rid of, followed by University engineering school surplus equipment and finally the once in a while old codger like me who has one they decided they just don't need anymore because Momma wants to park her car in that side of the garage, or an estate sale too.
Hope this helps!!!
Bob