A design of this type can be fairly labor intensive. That is the whole reason I am not building a Selah kit for now. I could build it in a more or less standard fashion but for what the drivers alone cost I feel obligated to go all out on it.In the meantime this seemed like a fairly straight forward project that would not cost much for the performance achieved. A lot of the bang of the buck came from the fact that this is a buyout driver and is probably a decent deal @ the $10.50/each price. If I get 100 of the the price drops over 40%. Couple this with a decently built enclosure (nothing over the top) and the price is about $350/pair. I agree with you about factoring in cost/effort/performance in any project. In something like this I can make some compromises dues to the lower cost and simple enclosure construction. I still think the performance would be impressive but I am doubtful that it would be amazing. For amazing performance I know I will have to spend $2k+ on a Selah kit.
Later,
Aaron