The HP 15C is priced between $100 to $200, primarily due to its nostalgic value and historical significance as a top scientific calculator for engineers and chemists in the 1980s. While it offers compact size and advanced functions, some users question its competitiveness against modern calculators, which may provide more features at lower prices. The 12C model, specialized for financial calculations, is cheaper but lacks the broader functionality of the 15C. Many potential buyers express interest in the 15C for personal use or as a collector's item, despite the availability of cheaper alternatives. Ultimately, the 15C's appeal lies in its legacy and portability, making it a unique choice for those who appreciate its history.