Back in channel 4 days, when each chair would basically become really iconic, they would either be auctioned off for charity, (Mario mole, bb11 owns the bb7 one) or they were kept by the channel for promotional purposes. For example, the bb5 chair toured the country with then sponsor talk talk, along with housemates of that series. The bb3 one was kept by channel 4, it has been used in a few other shows, such as doctor who, and reused in ultimate BB. The channel 5 days, however, I have no idea. They aren't really that iconic anymore unfortunately and there are so many in so little time they're not as wow worthy as they once were. The bb1 chair had a few replicas made, and I think channel 4 still has it on display at its hq.