18-Bracket Banjo Armrest?

I have this 18-bracket starter banjo:

http://www.musiciansfriend.com/folk-traditional-instruments/rogue-travel--starter-banjo/511195000000000

I'm really in need of an armrest, because my arm is taking a beating from the brackets. I'm a poor college student, so I'm looking for a decent armrest under $20. I don't know what kind I'm looking for. Can anyone help me find one?

Thanks