Another angle to think about if you have a friend with the ability to make loops for you. You could have him make them out for all your play list and email them to you as a MP3 file and put it on your phone or ipod.. cheap earbuds and you're up and running without a lot invested.
Also if your using an iphone,there is a great app called Tempo Advanced by Frozen Ape apps. This advanced version is really useful,I use it on the Opry all the time. You can log in the name of the song/tempo and select two sounds to hear at the same time. It also will will show up in a window as the song title , then when your set list changes, you simply touch and drag the song in the order of the setlist. Touch the play button and your off and when the song ends touch the screen again and it scrolls to the next song in line with or without ever stopping,you decide. It has a count off and multiple time sigs. I just bought the advanced version. I have been using the original Tempo version. It's not bad but harder to see but still works fine for short gigs. I had a friend that turned me onto the Tempo Advanced version and that's the way to go. Good thing is ,it only cost $1.99 on your itunes account.
I use a set of earbuds with one ear out when I am doing the live monitor stage. The iphone is more than loud enough to hear over live sound to the point if your not careful you can damage your hearing with the earbuds.
Hope this helps you!!!