hotmama, I have seen one on Cabildo. It was in the store "used to be known as MILOFT". I am not sure what the name of that store is now, I pass by there everyday and stubbornly call it MILOFT, even if they were bought out. The store is a block after the SONY store, but across the street from there. I will keep my eyes open for places that might carry them.
Try there first, just be warned of the high ticket price. But as far as I can remember they were made in Argentina. Good luck.
If you can't find one, there are quite a few sites on the Internet that discuss how to dehydrate foods using the oven.
There's also this link for building your own solar dehydrator is you're so inclined:http://www.thefarm.org/charities/i4at/surv/soldehyd.htm