Does anyone know of an inexpensive source for stock exhaust sections?

I have a 1987 5000 Quattro and it's pipes are rusting at the joints --
Over the years I've been visiting my local custom shop and they've
welded it here and there, but I think it's time for to replace from
the cat back.

I've stumbled onto Milltek and Stebro, but I just want it fixed for
cheap (and stock -- the last think I want is to listen to some droning
custom rumble for hours between Boston and New York).

PS, was the original aluminized or stainless?
Thanks.

PSS, this 5KQ needs some front end work, which I'll do myself, but it
has almost 300K on it. So I've considered replacing it with a 90-94
100Q, but those have iron blocks with aluminum heads -- do these have
an okay track record?
Thanks again.