I think that the way Nate Elston did it is the way to go. Get yourself an Aubers PID that controls a solid state relay. I bought the two together with a probe (K type thermocouple) for about $80. The SSR has more than enough power to switch your current element, and if someday you want to upgrade to say 1500W you'll still be in business. You'll need to also get a heat sink - I got mine out of my junked stereo receiver and you can find them in computers and other electronic devices or shell out $5 or so at Radio Shack.
As I had mentioned in a previous post, I'm converting my defunct MES 40 to a PID controlled smoker, but if I had any type of insulated box like an old fridge I'd use that. You can find 110V heating elements at almost any thrift store - I bought two of those table top electric grills and one had an 800W element, the other a 1000W element. I'm not mechanically inclined enough to build my own smoker and ended up with an MES that failed way too soon. Go for it - you can build a great smoker yourself.