There's a service here called "Home to Heaven" that does home euthanasia and that's all they do. They are so gentle. It cost $100 for a big dog; not that much more than taking him to the vet would have been.

I found this page searching for "home veterinary euthanasia madison wi"
http://inhomepeteuthanasia.com/index.php?option=com_sobi2&catid=50&Itemid=55
but I couldn't find prices on the webpages of the services it links to. I think you have to call each of them for that information.

I have ~$50 in my Paypal right now, which I will gladly send you to make Sorcha more comfortable. Send me your email.