For Berdan primers, contact North Sylva in TO. They are distributors for RWS. I know that they supplied Berdan caps to a CGN recently.
I have reloaded a fair amount of Berdan primed 6.5x55. Decapping is less convenient than with Boxer primed cases, but its no big deal. I have used a RCBS tool, and they work fine. I have also used an improvised setup - a hardwood block drilled to accept the case, slit on one side so that I could tighten it in a small vice to clamp the case. A sharp awl was then driven into the cap starting at the primer indent, and the cap popped out. Repriming is no harder than repriming Boxer. There is also the hydraulic method.
Generally speaking though, there is no point in reloading Berdan primed cases if Boxer primed ones are readily available. With some calibres, you may not have a choice.
Are you referring to the really cheap steel cased 7.62x25 ammunition? Don't waste your time.
If you had good quality Berdan brass cases, and were loading for an elderly Mauser pistol, it might make sense to consider reloading.