If worse comes to worst, you can always use a kitchen trash can. I've used them because my veiled never liked her small bin, so I'd leave her in a black kitchen trashcan with 12" of organic soil.
But if you have time to run out to the store, pick up an opaque, dark container that measures at least 12" deep, by at least 7-8" wide. You can fill it with moist play sand or organic top soil, both cheaply available at Home Depot/Lowe's.
But read Jann's blog for more details. I just wanted to say what I've used in the past.
With all that usually cost about $20 bucks and takes 2 mins to get ready. I usually leave the can in cage most of the time except right after she lays of course I take it out and maybe wait week or so to place it back in.