Is it common for the A/C O'rings to go out on a '96 honda accord. Are these something that can be replaced by an average accord owner or does it take a specailized mechanic w/ the necessary tools?

 

Not too common, but yes, sometimes they go bad.
You can change them yourself, but will probably have to take it to a shop to have the system vacuumed before recharging it, and might as well let them charge it at the same time. They can then monitor the system pressures and let you know of any other potential problems.