I've seen zebra otos twice: once in Bellevue, WA, and once in Bellingam, WA about 90 miles away. At both places I think they were priced at ~$15. Apparently they are somewhat rare.

Thanks for all of the replies. I think that I will try the collard greens method suggested by racoll as well as djw66's suggestion for growing algae in a goldfish tank.

To answer some of the other questions, the tank is kept at around 78 degrees. pH is close to 7. It sometimes dips to about 6.8 and ...

I'm very worried about my otocincluses not getting enough food. It seems like most of the algae in my well planted, bogwood-containing, 29-gallon community tank has been eaten. Unfortunately, I can't induce my algae-eating crew (1 common oto, 2 Niger otos, and 2 hill stream loaches) to eat anything ...