Typically folks have used Stayton Motor Sports for their Arctic Cat needs. They recently lost their dealership and Dan's Motorsports in Salem is picking it up, or at least that is what I have heard. Dan used to work at Stayton, but has since opened up his own shop. I would give Dan at Dan't Motor Sports Outlet in Salem a call and see if he can help you out. I think there was an AC dealer in Medford but don't know their fate and also one in Bend, but I don't know their status either.
Kind of slim pickings for sled dealers in the valley if you don't ride Polaris. Yamaha has a dealer in Sublimity, for what that is worth.