I've seen mk3 Mondeo, mk2 Focus and FWD Volvo 16" steels fitted on RWD cars, but it requires the rims being altered.
The idea being to cut the centre out and re-weld it with the desired offset (may require being reversed). Or you could get them banded to your desired width, which in turn alters the offset.
The 140 was effectively a FWD offset anyway, ~40-45mm. The 240, 740 and 940 are ~25mm
Another option worth looking at is
http://www.extremeoffsetwheels.com/custom%20made.html
You can get a set of 7x16 in any offset, any PCD for £350.
Or keep your eyes on 2nd hand sales, there's a 5x108 sales group on facebook for example
EDIT: There are some modern PSA cars that are 5x108, the C5 mentioned above, and Peugeot 407 to mention a couple