The problem with resistor type heater bands is that sooner or later your going to have a solder joint break in all of those connections. I tried building one and quickly realised that the production heater bands are actually pretty good value. The Dew-Not heaters are the ones I use now and the EP ones cost less than $30. Link here:
http://agenaastro.com/dew-not-dew-remover.html
Controllers are different, by the time you buy the components to build the one mentioned in the previous post you could have saved money and bought a good one from Arthur here on IIS who makes them for a very low price. He charged me $35 for a three channel controller that works great. He's not doing it to make money just to help people out. Send him a PM - Arthur Alchin.