Nick The two British dealers I would recommend are -------
http://www.hayaltd.co.uk
based in Cardiff and a dealer in Heng Long products,
The advertised prices usually do not include VAT or postage so you need to look a little closer at the product advertisement to discover its true price,
The dealer is not trying to fool you, He sells a lot of product to the trade where VAT and other overheads do not apply,
The second dealer is ---
http://www.forgebeartanks.com
Dave is a member of this Forum and is probably the straightest dealer in our hobby, He is a Taigen Dealer and when I need parts Dave is my first port of call,
Then there is "Nitrotek" Please save yourself aggravation and avoid this dealer, We get far to many Horror stories about them,
There is also "Tankzone" which some people big up and some people avoid like the plague.
Howes in Kidlington, near Oxford is an old fashioned Toy Shop with an on line shop selling a limited range of Heng Long armour, -----
http://www.howesmodels.co.uk
The advantage is the prices are low the downside is that it is a toy shop and not a specialist dealer BUT they will not abandon you if you have a problem.
Now we come to Dominik at ------
http://www.rctank.de/
As you see it is a German based dealer who also sells Taigen Products,
And if you are interested in Tamiya Tanks Axels is also in Germany at -----
http://www.axels-modellbau-shop.de/katalog/en/
I do commend Dave, Dom and Axels,
There is another British Dealer ----
http://www.welshdragonmodels.co.uk
Steve is another one of the Good guys with a variable stock availability.
I hope that helps,
Other members of the Forum will have their favourites I am sure.