I've dealt with two other online tube sources in the past and have had excellent results.
http://www.hamtubes.com and
http://www.vacuumtubes.com
No connection with them other than a satisfied customer.
Both of these guys provide excellent service and quick shipping. In one case, a tube ordered one afternoon was on my doorstep by the next. Looks like the prices on 6JS6 are 1/2 to 1/3 of the AES price.
-Jim