* Size: The larger the drawing, the more valuable it is likely to be.
* Medium: Drawings created with more expensive materials, such as oil paints or charcoal, are typically worth more than those created with less expensive materials, such as pencil or ink.
* Provenance: A drawing that has a clear and documented history, such as one that was owned by Elvis Presley himself or that was exhibited in a major museum, is likely to be worth more than one without such provenance.
* Rarity: A drawing that is one of a kind or that is part of a limited edition is likely to be worth more than one that is more common.
* Condition: A drawing that is in good condition, without any damage or wear, is likely to be worth more than one that is in poor condition.
* Market Demand: The overall demand for Bill Mack drawings of Elvis Presley can also affect the value. If there is a high demand for such drawings, they may sell for higher prices than if demand is low.
With all these factors considered, it is difficult to give a precise value for an original Bill Mack drawing of Elvis Presley. However, some recent sales of such drawings have ranged from a few thousand dollars to over $100,000.