I use Holga's both in Pro and Am work.
A holga is a *wonderful* tool. Load it with 120 black and white film or slide film and off you go to make mistakes by the bucketload
I belive if you're passsing through Chicago, Central Camera has them in stock for about $30 for the basic one.
I found that it slowed me back down in photography terms (and they're fun to use in the plane... and since they'res no electronics, its safe for them to be used)...
(PLUG: there's a few holga images of mine in "Why I life flying in an image" thread)
Highly recommended. ^