1) Closest to extinction 2) First served 3) Found least often 4) Going for the most on eBay 5) Hardest to come by 6) Hardest to find 7) Hardest to get 8) Hardest to get hold of 9) Hardest to locate 10) Hardest to obtain 11) Least abundant 12) Least available 13) Least common 14) Least cooked 15) Least dense