Hi Ken,
I have a few different FEG shotguns. The O/U is rarer than their SxS's. Keep in mind that these guns were sold at Sears and Canadian Tire in their day. I find them VERY reliable and very tight, a well made SG. I think a FMV for you and for purchaser is in the $300-$400 range, condition being the factor of course. This is only my opinion as I have never paid more than $275 for a Feg.
Shawn (12Ga.Messiah)