My advice:
Buy the material & have it welded in place. I had spent roughly $150 for 3" SS pipe & mandrel bends, $70 for a SS vibriant resonator & another $70 for a SS Magnaflow muffler. I think I paid around $60 for the SS hangers & flanges. My partial SS DP (just a V-band flange with a 90 on it) was part of my turbo kit so I'm not sure of the exact price, but IIRC, it was $100.
That's $450 (plus the cost of labor for welding) for a full 3" SS, mandrel bent exhaust, including the DP. I love the results too. While I'll admit my opinion is biased, I have to say that the fit couldn't be better (thanks Aaron) & it's one of the most free flowing, best sounding exhausts fitted to a MKIII. The price can't be beat as well....