What kind of lock is it out of? I have a coupla original tumblers and assorted parts that I might never use. So if there is some way you can send a life size photo or tracing, with dimensions of the axles, I might have something that will work. Though using tracings or photos might be a little sketchy. Not to mention that finding an old tumbler that will drop in without some modification will be nearly impossible.
There are a lot of folks on this forum who might have an odd tumbler or two lying around gathering dust, so maybe posting a photo of the inside and outside of the lock, so's we can get an idea of what type and size of lock you have, and what size tumbler you need, might encourage someone to offer a spare part.
IMHO, the best option short of having someone make a very expensive tumbler, is going to some sort of large event with vendors who sell locks and parts. Take the whole lock with you, and a turnscrew and a container for your parts, so's you can match parts to your lock.
And as mentioned Larry Zornes might be a good source.
God bless