I sold a A5 with a Poly Choke about 5 years ago, I got $550 at auction but it wasn't in the greatest of shape. I have seen barrels with Poly Chokes for around $200. Also I recommend confirming the authenticity of the installation as it could add a bit to the desirability of it. You can do this by unscrewing the choke revealing the collar. On the collar should be a number which is the number for the authorized Poly Choke dealer (a 1 or 2 digit number). As per the Shirley and Vanderlinden book, dealer number 11 should be Browning and dealer number 9 should be Fabrique Nationale. All other numbers are authorized dealers, and if it does not have a number it was not installed by a authorized dealer or Browning or FN.