Being the neat freak I am, I left the platic bag it came in on my ipad.
It works great so far and keeps it clean.

Eventually it will get too dirty, so I was wondering if ther was a source for more of them.
I like the idea of just replacing a simple plastic bag.

This is just a personal bias, but I don't enclose circuitry in plastic bags once it's been exposed to the open air. Closed plastic bags do a good job of trapping any ambient moisture and circuitry doesn't mix well with moisture.

Yes, if you leave it in a sealed bag you would need to keep a desiccant bag in with it.

Good advice!