You can order the seperate parts or maybe even pick them up at a local store.
Below are some examples of items that can be used. The radius is also important if you go to do this. If the radius is too wide you may hit the shock tower.
I think if you measure everything ahead of time and mark it a local welder might do a couple welds for under $50. Maybe cheaper if you just walk in and hand them the pieces.
As where I have not had one welded yet, I have mocked up a couple different sizes, with flanges and different radii. There are sellers on ebay that will custom make a flange for you if they do not have the size readily available. I had one seller make a 3" exhaust for the outlet of the turbo.
