I was bidding on this poster in the John Peel auction earlier today, I set my limit and then someone beat me on the next bid, ah well - I considered bidding on some BBD records, including white label test pressings but they were going for silly money.
The rarest BBD thing that I have is the belt buckle. I don't think that they were very common. I have no idea what it might be worth.
I still have an original Axe Victim promo-poster from 1974,..The one above sold for £220😲
I also have one or two 'quirky' bits of memorabilia, such as a Sunburst Finish advertising banner, a BBD 'Koncert Kit' paper carrier bag, that was sold at Drastic Plastic concerts (I think DP), to put your merch, programs and goodies in.