I just picked one up lastweek and heve used it 4 times already. It makes cleaning out the 5 gal carboys a snap. It's worth spending the little extra to save tons of time and frustration scrubbing with that brush.
PB2 is a good substitute. It's expensive, but it keeps you from having to give up 10+ days de-oiling the peanut butter on your own. here's a link. They also have a Chocolate Peanut Butter. Though they are currently out of stock...