A/C and terrible odor

[segal at cop.ufl.edu]

I have a 90 90Q20V and the A/C stopped blowing cool air.  When
I turn on the A/C, instead of cool air, I have in place is a
terrible odor.  Apparently, I am sonething as simple as a recharge
or something that would suggest $$$.  Pls advise whether the
sequence of events is suggestive of a recharge or something else.
 If the former, what are the disadvantage/advantages of alternative
recharge gases?  Any ideas about fair prices for ths work.  Thanks
in advance for any assistance.

Rich