Start by revieiwng the info on the air pump replacement procedure at:

http://volvospeed.com/bay13.htm

maybe you can do it yourself. It should also list the parts so you
can at least call around or check with online parts discounters and
see if the parts prices are reasonable.

Also, check your warranty info in the onwers manual. The air pump
is part of the smog system and some states have minimal warranties
on emission components that exceed the manufactures warranty. California
is one example.

You should also search the archives (below, to the right) for
"air pump" and see what others have done.

You could also do nothing. I don't think drivability will suffer.
If you have an emssion test in your state then eventually it would have
to be fixed but maybe you can time it better to fit in with your
income tas refund :)