Sabah and Sarawak stamps used in Brunei

These stamps ended their ebay auctions last night. Even though I put a bid, I don't think my bid is high enough and I am still smarting from the postcard purchases. Anyway, it ended somewhere around midnight and the winning bid was in the US$150+ range about twice the amount of my highest bid.Why did I try to get these stamps? These stamps are fairly unusual, well at least one of them is unusual.