finamore, It sounds like the batteries are pretty expensive even if they can be found. Have you considered having your battery rebuilt or even rebuilding yourself. You could end up with a pretty good battery for a lot less. I will post a couple links for you to check out, but do not be afraid to google search for your self as there are lot more sites to check out on both Having your battery rebuilt or DYI rebuilding guides. Good luck.
I hope this helped you out, if so let me know by pressing the helpful button.
http://www.thesource.ca/en-ca/Battery_Rebuild
http://www.notebookreview.com/news/diy-laptop-battery-rebuild/