1987 carling black lable can promotional can extra free. collectable, bar orniment ect in Middlesbrough, Durham for sale

I have hear 3 x 1987 carling black label cans with the 10% extra free promotion on rim, and no sorry the drink has gone. I've held onto them for some time but just trying to get rid of some stuff at home. what are these worth????? they are rare. to a collector? I don't know. as an ornament or future investment? I wouldn't know where to start looking for a value. quirky fathers day present.... pub owner.... home bar ornament..... ect ect I want £10 each for them, am I being stupid fair or optimistic I don't know. I just hope I don't see them in the news or something sell for thousands lol. "but you do see it happen". I believe in there worth what someone will pay for them... I personally wont sell them for less.