I would not go with an air sander they take need a big compressor to run one as they use allot of air. Porta Cable makes a very nice palm sander which shold work grat of fixing gouges which usually do not require heavy sanding. They have two models one you can adjust the speed or the one I linked here which you cannot adjust the speed but will work just fine (this is the type I have.
http://www.toolbarn.com/product/portercable/343K/ You can pick one up at Lowes for the same price as the toolbarn.