Condition: Proof coins are specially minted and handled with care to preserve their original condition. The value of a proof set increases as the coins are in better condition. Factors such as surface marks, scratches, or toning can reduce the value of the set.
Packaging: The original packaging can add to the value of the proof set. If the set comes in its original government packaging, such as the plastic case and outer box, it is considered more desirable and valuable to collectors.
Year and Mintmark: The year and mintmark of the proof set can also affect its value. Proof sets from certain years or with specific mintmarks may have lower mintage figures, making them rarer and more valuable.
Availability and Demand: The availability and demand for 1981 US Proof Sets play a role in determining their value. If the sets are scarce or highly sought after by collectors, their value can be higher.
Based on these factors, a 1981 US Proof Set in excellent condition, with original packaging, and from a sought-after mintmark, could be valued between $15 to $35. However, it's important to note that the actual value can vary and it is always advisable to consult with a reputable coin dealer or numismatic expert for an accurate appraisal.