If the regulator is so old that it cannot be fixed, then you probably need to look for another regulator. This is why buying used regulators can be such a good deal. Tanks Check the hydro and visual testing dates on the tank, and make sure it has passed these tests. How often these tests have been performed in the past also gives some idea of usage over the years. For wetsuits, look at the seams, the knees, etc.
Gloves are notorious for wearing out quickly - pay attention to the fingers.
How many patches the drysuit has is also a good indicator of its condition. Test the inflator valve and the seal. Where to Look Of course, how good of a deal you can get depends partially on luck and partially on how much you look around. Here are a few places you can look for used gear. Local dive shops - Dive shops often sell used rental gear at reduced prices.