The Akai APC series was one of the first purpose made controllers for Ableton Live. As such, the layout is super intuitive and easy to understand, as it maps pretty much directly to Live’s Session View.
This is a video I did reviewing the APC 40 MKII, I go through the features and how it works with Live.
The price has actually come down since I did this video, you can usually get these for around 299 or less.
Either way, it’s a great way to control and interact with Ableton Live.
Here’s a link to buy it if you dig it: http://www.zzounds.com/a–1786589/item–AKAAPC40MKII