I found a bunch of clayboard I had saved up from...something or other.
I have only nine of them left over and will use them for commissions until I'm out.
They're pretty freaking awesome for fur detailing and typically have a pretty brooding/moody appeal.
They can be colored traditionally or digitally, as well!

Full (7x5 in)
Example 1
Example 2
$40

Small (~3.5x2.5 in)
Example 3
Example 4
$25