Does anyone build single kit?
 

I'm think about this.

using T04e and hks wastegate.

I think turbocharger, wastegate and manifold are not a problem.

But I think downpipe gonna be a big problem.

Do you guys know where can I fabricate it?

You might be able to buy one from XS Engineering, Rotary Extreme, or maybe even HKS.

why not just buy all the parts i havent seen any kits like that

if you know how to weld then the dp shouldnt be a big problem. You need some ss tubing with U-bends(thats just to give you a idea). Im sure someone who has little more knowledge can tell you exactly what you need(thickness of the tubing ect..)
Other option is to go to a closest turbo shop or someone thats really good at exhuast systems(muffler shops) and have them make you one. Should be cheaper than buying one though.

Thats another option, you can get mandrel bent pieces from Burns Stainlessand ATP Turbo.

What I would do is buy the turbo with your specs from someplace like cheapturbo.com, get the manifold from a place like the RX7store.net as well as the wastegate and get get the piping and flanges from atp turbo. They can also help you out with oil and coolant lines. For around $1,500 you have a turbo "kit". With the left over piping from the downpipe you could make ic piping and weld your BOV.
It isn't really all that hard if you are handy and have the resources, you just need to know where to look.

cool, I may do this.