I posted alooong time back, about a year, on how to make some homemade "tyler grips" They worked ok. This is far simpler.
I put a full post up on my site -
http://synergy-athletics.com/?p=2115
but here is the jest of it.
Take a bar bad - 10-15$ based on where you get it, I actually think they have them at walmart.
Cut it in half.
Just snap it over your DB handles or your pull up bar...Done.
Yes, they are a little softer than tyler grips, but crazy simple and easy to make. Literally just need a pair of scissors or a knife...