I love the lots of money and time comment.
First, my time for me is free.
Second, I have the thermal coating I'm going to use already. (Leftover from the engine(s) that I've done in the past years.)
Third, I have the MIG, and only need to buy the wire.
Same with the die grinders and bits. I have them already. Same goes for the sand blasting cabinet etc... Yada yada...
The biggest thing about this, and the one item that trumps them all, is that I enjoy welding, modding and porting mechanical parts. So it's really not a waste of my time, or my money, but more like fufillment of a hobby.
Besides, you can't even buy the flanges and pipe as cheap as you can buy the completed manifold. (Priced 321 stainless lately? Not very cheap, and you have to cut every piece, and fit, and weld it all up etc. Mod work is much less time consuming if the basic foundation is somewhat correct.) These have been bashed, and applauded, but the basic truth is they work, and work well. Especially for the money spent.