I suspect you can find a couple of cheap 14 inch wheels for the 240D on eBay if you keep looking. Here's one listed now:

http://cgi.ebay.com/ebaymotors/MERCEDES-5-1-2-x-14-WHEEL-111-108-113-114-123-116-107_W0QQitemZ8018731926QQcategoryZ43954QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

The 14 inch wheels seen to be cheap because no one wants them. I would also try the local junk yards for both cars.