I run Hoskes on my r90. I can't remember how much they were...something like $450 or so (definitely under 500.)
I ordered them through Wes at Apex Cycles. He gets them from some guy that makes them still in Germany.
You can also still order them from seibenrock
I really like them. They have an incredible sound with out being too noticeable and annoying on the highway. They do have a bit more flow than stock exhaust. You can probably be find with stock jetting but Wes has been toying with a 50 idle jet and says he's getting a good power range with that.