Reply to 2 channel mixer for mobile setup w/ iPad

Hello I'm looking to buy one cheap 2 channel mixer (at least) to use as mobile setup with my iPad.
My idea would be iPad + audio interface and the mixer. I know that the Z1 would be perfect but I trying to find a cheap solution as I already have an audio interface.
I use either DJ player and traktor DJ, I'm still trying to find out which one is better.
Any suggestions?