Exorbitant is the word that fits the best - it usually describes a disproportionately high price for what you are actually buying.
Buyers at auctions for items owned by famous individuals often pay exorbitant prices due to the rarity and historical significance of these items. The term 'exorbitant' indicates these prices are unreasonably high. Such demand exemplifies how collectors value celebrity memorabilia significantly above its material worth.
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