As far as DIYER experiences go, it seems to me that "someguyfrommaryland" has been down this road as much as anyone here. Check out the thread below.
It would appear that you can easily operate without it if you're not hampered by local environmental laws. If cars are tested for emissions in your area, I suppose you could be required to fix the darn thing.
It also appears that becuase of parts availability, etc., it's one of those items you're forced to buy new or rebuilt and from what I can tell, neither one is very cheap. My research in the SEARCH facility here indicates that bearing failures are about all that goes wrong in the ones used in M103 systems.
DIY Air Pump Rebuild Possible?