When I first started out in wet plate photography it took me a substatial amount of time to locate suppliers here in Europe. Initially I wanted to mix everything myself and hence was looking for a supplier to sell me all the raw chemicals. Along the way I realized that especially cadmium bromide and ether (both goes in the collodion mix) isn't really something I want to have laying around my house in raw form. Once I get a proper studio space fine, but right now I share this house with my own plus another family and work out of our basement. That's four adults and four small children running around. Look up the safety sheets for those two things and I'm sure you'll get the point.
So I opted for doing most things myself, but I'm buying the collodion pre-mixed.
Most of the suppliers listed online and in the books are American, but there's light at the end of the tunnel for you, if you happen to live in Europe (or even Denmark) like I do.
Here's a list of the suppliers I've used so far:
Mamut Photo, Pragh
They carry everything you need and are based in Europe, so no import taxes or other craziness. I get my colldion, hypo, aluminum and silver there. Shipping is a little steep, but they're really fast.
Wet Plate Wagon, Barcelona
After seeing one at Quinn Jacobson's studio in Denver I ordered a dark box from Rafel. I don't have a dark room at home, so this is how I started out and it works like a charm. He also made a silver tank for 8x10 plates that fit's right in.
Incamera Industries, Portland, US
I stared working with my spare 4x5 camera that I've been using for film photography and Jody Ake's holder works great. It takes 4x5 aluminum plates in full size.
Lund Photographics, US
I got a drying rack from Lund. This is somewhat of a luxery item, but I really like tey way it can be used in the washing stage, especially since I use a lot of hypo which takes longer to wash.
There's a bunch of other little things you need, but most can be picked up at you local hardware store. One exception is all the beakers, bottles and other glassware. Those I got from a local company who serves the chemistry departments in local high schools. They also sold me glacial actic acid and denatured alcohol.