I haven't bought Al Waha in a long time so I'll let someone else recommend a vendor.
AF Soft Black is currently only available from two places online (that I know of). www.hookahset.com
and one other vendor.
Desi Murli is available from two vendors. www.hookah1.com
Since hookah1 is 'the source' it will be a little bit cheaper and has a greater variety.
Zaghloul anymore is carried by pretty much any vendor that carries Nakhla.
But I'll give you a hint:
If you order some DM from hookah1, scroll down the page and order some Salloum Plain. Virtually the same product, but is only $5 for a 250.