Whats a B&K Reference 2220 600 W Amp worth?

I just moved into a new house and two B&K reference 2220 amps were left behind with the old home sound system. We have converted to Sonos and no longer use them. I think they are about 10 years old (or more). Are these things still used? Any idea of value?
You have come across a nice find. If in good shape(cosmetically and operationally), they are "worth" $350.00 to $450.00 each. They spec at 220w/ch@8ohms and I think 350w/ch@4ohms.