Insurance can cover part of the price, so check your coverage (it's a medical device, just like crutches, etc.; you generally need a prescription and then you buy it from a medical supplier or a well-stocked pharmacy). I use a small machine by "Sunrise"; it's slightly smaller than a big-city phone book.

You can also check eBay. I know a lot of hobbyists buy and sell nebulizers and use them as inexpensive paint sprayers!