Tetraboy/Seb,
I have had two orders delivered by Tri_Mar and they come very well packed, the fish seem totally unstressed and all fish have been alive and healthy on arrival.
The quality of the fish is good as well as the owner, Monty, believes that they shouldn't ship fish he would not want to own and it also saves on returns/complaints. They can often get hold of rare and unusual fish for you.
The delivery charge is £10, but a lot of the fish are cheaper than in my LFS in London, also you can make up for it by getting various dry goods, etc. at the same time.
Cheers, Eddie