I just use a glass bowl with sanitized foil over it. Also used gladware containers and empty juice jugs. I sanitize with star-san, or a run through the dishwasher to sterilize. As far as I'm concerned, a starter can go in anything you can keep clean for a day or two.
Disclaimer: only two of my beers are carbed and ready to drink, so maybe don't listen to me
Primary: Belgian Dubbel Braggot
On Deck: Sour-mash Belgian Strong
Bottled : Holy Matrimony Saison, Ghost Stout (extract), Blood Orange Hefeweisen, Oatmeal Stout, Willamette SMaSH lager, EdWort's Apfelwein, Scottish Export, Cascade SMaSH, Amarillo SMaSH, Ghost Stout (partial mash), EdWort's Apfelwein, Cranberry Wheat, Habanero American Ale, Belgian Christmas Ale