I've been using a 5-gallon water bottle for two batches of Skeeter pee. It happens to fit a standard 5-gallon carboy cap. The cap is tight enough to allow the airlock to bubble, which means it won't let nasty critters in. Unfortunately the seal is microscopically loose enough to not work when I blow air into the cap to force the liquid through a racking cane -- the pressurized air escapes out the bottom of the cap.
The bottle was available at the local big box store for $7, near the water filters. It is marked as food grade.
There have been no big, flavorful beers in this bottle yet, so I can't comment on its ability to resist absorbing stuff.