Sold by the linear yard usually referrs to something that has width in addition to length but the length is used to determine price. And example is fabric/cloth -- it's sold for so much per linear yard, meaning how long a piece you want. The width is included in the price per yard.
The price of leather depends on its type (cow, pig, deer, etc.) and quality. The size of the hide determines the maximum length of the piece, and since larger pieces are more likely to have flaws the price for a relatively flawless piece can increase significantly.
allocative function of price: to direct resources away from overcrowded markets and towards markets that are underserved. Rationing function of price: to distribute scare goods to those consumers who value them most highly