The HL tanks can be found on this forum for starters. I'd say that roughly 2/3rds of all posts here pertain to the Heng Long tanks, at least from time to time.

Otherwise, they can be found for sale all over the net like from this comparison shop site:
http://www.shopzilla.com/7S--Robotic...ox--1__sfsk--3

Heng Long makes a Tiger I, Panther, M26 Pershing or "Snow Leopard", M41 Walker Bulldog.

Videos (I recommend these all the time it seems):
http://www.youtube.com/watch?v=uHtbv...elated&search=
http://www.youtube.com/watch?v=IIadL...e=user&search=

-Harq