OK, some UK based ones as buying from the USA needs a lot of paperwork and is not really viable
Sorry, I missed this thread initially.
Actually they are not all UK based. Buying from Europe can be good and needs no paperwork.
In the UK I like
Burnham Orchid Nursery and have visited them down in Devon a few times.
I used to also buy mail order from David Steed, but he emigrated and no longer sells orchids in the UK
There are other UK based ones I have bought from while at shows and who also do mail order (I've just not tried their mail order so don't know how good they are at packing the plants etc).
Ratcliff Orchids
Laneside Hardy Orchids - these are orchids for the garden
Heritage Orchids - really great pleiones from here
Kool Orchids
Ray Creek Orchids
Then a couple of German based ones.
Großräschener Orchids I've bought from them a few times but shipping is not the cheapest. So I usually buy a few at a time as shipping then works out better.
Popow Orchids - I've not used this one, but orchid board member Camille has and been very pleased with them. They also sell on ebay and can be cheeper there. Camille has bought from them on ebay. They go under the name lepantes there though. They generally have good shipping charges.