I am all for things like this. Homebrew over pre-made for a cheaper price. In fact, that's why I (and other people) chose to build a homemade VGA cable for the Xbox 1 instead of buying an X2VGA for $70 or however much they cost. It was easy, a learning experience, and very cheap.
This, although very much the same thing, isn't really necessary though. With the Xbox 1, there were no other VGA options except for expensive transcoders. With the Xbox 360, you can just get a $15 generic VGA cable on ebay. In fact, that's probably right around the cost of the normal A/V cable. So, you're not really saving anything with this mod. I love the idea, and would do it, if not for the cheap VGA cable already widely available.