It seems like the going price for A/C service is $139 or so.

Can anyone recommend a shop in the Rockville/Bethesda area to do this service? Perhaps even for a little less?
I need to take it in, have the system evacuated, then bring it back later to have it recharged.

(it's not the S, it's my 1970 Beetle - still using R134 refrigerant)

Thanks!