I know you wanted something really cheap, but just in case you cannot find what you want, Goldpoint makes some very nice variable attenuators. The SA-1 is the simple stereo RCA interconnect version at about $300. Very high quality units (I have a couple) and you can attenuate your signal at any level you want.
http://www.goldpt.com/sa1.html
http://www.goldpt.com/sa1.html