Steel sheets are generally sold by the size instead of the weight of the peice. Depending on the thickness of the steel sheet the price may very well vary. An example a thinner steel sheet of 12 inch by 48 inch should cost around thirty to forty dollars. However something much thicker could very well cost a few hundred dollars, sometimes it exists in the thousands. Sheet metal is usually sold my square inch. The thickness is taken into account when finding prices. For Example a 24x24 sheet of T-301 .016" thick stainless steel sells for 100$.