NDKoze,
No doubt about it, built in is nice and convenient. One downside is that when you lose the control board, you have lost your smoker. With the Auber (free with the model 4), if it dies, you still have your smoker. If you look at the CS smokers, parts, you can see just how expensive a digital replacement controller is; much more so than an Auber. AND: There is in testing stages, a model 2 with built in digital, so you may want to check that out.
There are pros and cons for both built in and add on. If you follow the postings regarding the Auber and the innovative way one particular fellow connected his, you will have the best of both worlds.
As for the shipping, well, some of the cost could be built in to the price of the smoker (mark up + hidden fees) in order to achieve a perceived lower shipping rate but then the competitive pricing edge is lost. And the packing that SI units come shipped in is very substantial and that adds to the cost. I know nothing about the cost of doing business from manufacturing, handling, shipping etc. But I imagine the profit margins are just slightly higher than slim.
Well, that is my take on the subject. It never hurts to ask.
Happy smoking.
Dave