Sometimes if you find a church that's closing down you can get one as well. You could also search on Craigs List or check if there are listings on The Organ Forum. I also believe that there is an Allen dealer close to (or in) Indianapolis and they probably sell used ones (although I'd bet they're more expensive that way).
To participate in the discussions on Catholic church music, sign in or register as a forum member, The forum is a project of the Church Music Association of America.