Dave:
You could also try AirGas here.
http://www.airgas.com/browse/product_list.aspx?catID=198&Page=1&filter=0|0|4|2|50726f6475637473|0|1|12||0|4|50726f6475637473|43617465676f7279|0|1|198|1|4d616e75666163747572657273|1|1|1466|0|0|3|50726f6475637473|437573746f6d657220436174616c6f6773|1|1|14262|0|0|3|1|1|0|&mfrID=1466&Keyword=&isFiltered=True
Prices seem reasonable, and they say, will be shipped from manufacturer (ThermaDyne?).