Where I live in California, they are free, believe it or not. Glad to see that my taxes are actually going somewhere that I use
(but I would rather not use them, if you know what I mean)
I know a lot of states have animal health facilities that will do them free for the backyard flock owners. Just check with your county ag office, they should know.
Here is another really good article on Marek's.
http://www.firststatevetsupply.com/poultry-health/mareks-disease.html
There is quite a bit of confusion around the vaccine. You will read that people think that the vaccine makes the bird a carrier for life, and that is not true. I wish, wish, wish, that I had had mine vaccinated when I first got them. The breeder I bought them from is a very nice lady, and does things very naturally and has never had any problems. And then there is me.
This disease can cause paralysis, blindness, wasting away, no symptoms, and sudden death, to name a few. So how exactlly do you fight something like that. I feel like I am fighting the Borg on Star Trek. The whole "we will assimilate you" thingy. I feel so helpless.
I did order the vaccine today so hopefully I can stop this before it goes any farther.