There's the mighty cleaving weapon property. As said above, it grants you an extra cleave per round.
Beyond that, an item that just flat-out granted you the Cleave feat would cost 20k, going by the items granting feats guideline in the Arms and Equipment Guide. 10k for the base feat, plus an additional 10k for each pre-requisite feat it has (in this case, Power Attack). If it's a wonderous item, bracer or gauntlets would be the appropriate slots. Or a weapon. I'd let a weapon count as appropriate.