Note that Williams' price includes Fenton-ish headers. That brings the price for the plumbing down to be in line with Don's quote.
Patrick's setup is priced without headers but is stainless steel and I believe is mandrel bent. I haven't heard one but all the reports are positive.
Also, Don, I not had the same experience as you with muffler shops.
Here in the Dallas/Fort Worth area, I've never found any muffler shop that has a mandrel bender. Most don't know what I'm talking about, and those that do wish they could afford one.
regards,
Leon