sorry I'm very late joining this, but have you checked your local 'dump'? Or recycle/transfer station? They often exchange stuff like bubble wrap for people. Or buddy up with a local store that sells trinkets?
I think if this were true the poultry industry would have stopped vaccinating a long time ago. It's important enough for them to have developed the technology to inoculate in vivo now. And no one wants to cull if they don't have to.
I have, and I have contacted some people but it's super tedious to look through them all and figure out where egg fruit is from. Also I can only send 2 messages a day because I refuse to pay for a membership apparently.
You don't vaccinate them. They naturally acquire immunities to a virus very similar to the chicken form of marecks. So when the chickens are exposed, their bodies create immunities that will work against most forms of the chicken marecks.
Some people give them decent lives before their expiration date, which is more than they would get otherwise. At least they aren't a total waste. That's worse I think.
First State Vet Supply will send you stuff to separate it, but unless you're hatching 200 at once, you still waste a little. But better than the whole bottle. The vaccine is a pain, but well with it. Marecks can wipe out a whole flock.