The '82 and '83 coins (all denominations) are a condition rarity. Some have begun saving AU grades, but the current demand is for mint state coins. The situation back in the early '80's had forced federal budget cutbacks. One of the items was the production/distribution of mint sets in '82 and '83. There were none. Souvenir sets would be produced and only available at the respective mints. If you wanted a mint state coin for your collection, your source was either souvenir sets or the initial release of circulation strike coins. The problem was that saving rolls had grown out of favor by the earlier '80's. And the usual annual distribution of Mint Sets for collectors was not to be. The news of the unavailability of Mint Sets became aware to the numismatic community after the yearly production had already been released into circulation. Consequently there is a restricted supply for mint state coins to satisfy the demand. Now, the quarter has a higher demand than the other denominations as the influx of State Quarter collectors has expanded their collection to include earlier issues of the quarter. Back in '98, the roll prices for quarters were similar to those that you quoted for halves. If there ever is an increase in collectors of the other denominations, then they too will enjoy a surge in prices as there is a restricted supply in mint state specimens.