I've been making and using collodion dry plates for several years. You'll end up having to make them from scratch as I've seen nothing out there ready made, and I doubt there would be much of a market. It isn't that difficult to make them, and it gets less the more you do. The Silver Sunbeam is a good place to start, and the tannin process is as good a one to start with than any.
I get most of what I need from Mike at ArtCraft, and he's been helpful in running down a few rare items I needed.
Collodion dry-plates have some great benefits, starting with the fact you can use them in all temperatures from the worst of summer to the worst of winter, and you do not have to have the darkroom there with you where ever you go. You can do them at home later the same day or over the next day or so if necessary.