Barry,
There are a couple of places just outside of Boston (Massachusetts) that work on rims. Straightening, widening, refinishing, etc.
Even if you shop hard, it still averages around $125. per rim. You shouldn't spend that kind of coin on a Marathon wheel, they're just too common.
Check here:
http://www.thesamba.com/vw/classifieds/search.php?submit=yes&keywords=marathon&type=text&stype=all&username=&yearfrom=&yearto=&pricefrom=&priceto=&model[]=§ion[]=25&wanted=show&zip=&zipdist=0&state[]=&usaregion=&country=&sort=date&sort_order=DESC&submitButton=Search
I got a set from the guy from Rutland, MA who's selling another set on TheSamba for $300. I can recommend him highly, his wheels and everything that he sells is top quality.
Luck,
FP