I had my tranny built(and recently serviced) at Hi Tech Transmission. They're at 1401 East 11th st in Tulsa. P# 918-582-7801. I don't know if they're resonable or not but I'm happy with the service.
EDIT: Rockauto doesn't list a clutch seperatly, and I don't believe its availible (oops). When the clutch goes out, it usually takes the compressor with it on those sanden/mitsu compressors, or at least that's been my experience. Perhaps a straight auto a/c part company might list them.
Or ebay....
http://www.ebay.com/itm/Dodge-Ram-25...#ht_1315wt_846