here's a review of the kettlestacks from some knowledgeable people
http://www.t-nation.com/readTopic.do...itan?id=472066 (I apologize for the long html)
another viable option that is cheaper than kettlebells are the loadable ones made by detroit barbell. I can't vouch for these because I haven't used them. Also an interesting site for fitness is
www.milfitmag.com, its run by nathanael morrison, and a few other people involved in military and LE training.