on your cost breakdown you have forgotten one very important cost. TIME from the time you decide to do this project till it actually runs correctly....................................
Now i didnt pull this stuff out of the air, my buddy did this project this summer and did hours of research to find the correct turbo, then finding the best price on parts which you dont get to order from one supply house, do the math.
But if your time is worth $$0$$ it would be cheaper to build your own kit, so I dont agree!! my time is worth way more to go ride but you may not take that into account.
Doug
Ok Doug since you dragged me into this mess.....lol I'm the guy he watched this last summer.
I have to agree with Doug, if............you have a stock motor that kits are available for and you are not at all interested in how the thing works. I would certainly buy a kit from one of the fine builders out there. If I was in that mode and I wanted to save some money, I would look for a used kit from one of these folks.
If you really want to figure this stuff out..........or you have a perfectly good, older technology motor like I did, then you start researching and building. I was very lucky. I had a fellow(Gus Bohne) who helped me a ton with setup info and turbo selection. I also have a good riding buddy(BManke) who has been running turbos for about, 12 years help me out. Not to mention I am fortunate in that I could do all of my own fabrication and have been tuning sleds for a year or ..too many.....LOL
I also had a lot of advise(not directly about my project) at various snow shows from the fellows at OVS and Twisted. These guys took a ton of time to explain the theories and reasons for nuts and bolts differences of their kits.
I had a absolute ball, learning how this and that worked. I am amazed at the rediculous power. I have definitely had problems that cost me rides. I don't know where you could buy the kind of knowledge, I gained. So if ya factor in the cost of that education, it's more expensive to build it yourself. But at least when you sell the sled or turbo, you still have the knowledge ya gained........good luck!