First, you should check the Optiswapit forum located on this website. Failing that, you should regularly do searches for “optigan” and “optigon” on eBay. Another potential online source is Craigslist. If all else fails, put an ad in your local classifieds, not under the “Music” section but under the “Garage sale” or “Wanted” section. You should also keep an eye out in your local thrift stores, but searching for one this way requires great patience and persistence. It helps to live in Southern California, though, because that’s where most Optigans ended up (the original factory was in Compton, CA). The advantage to these last two search methods is that if you DO find an Optigan® this way, you’re likely to pay MUCH less for it than if you found it online.