I was able to get a replacement seat for my B7510 over the weekend. Paid ~$31 w/tax. Have not had a chance to use it beyond installing and sitting on it. Seems to be a lot better seat, wider more cushion etc. I have heard yes/no on whether it really covers all current BX/B series. My dealer also lives on my street so he may have been helping me out. I too was shopping around for a replacement and they are $$$!
What I did that helped, is only use one of the rear springs and install in place of the rear bolt on the toolbox (under set). I eventually got me a long bolt so I could adjust the rear height of the seat. It at least helped to make it more level. Something to consider for those who are unable to replace their seat.