An interesting article that talks about current trends.
In summary: Pre-1840 is hot, flowing hair and bust coins are in serious demand. More buyers are seeking out higher quality for given assigned grades. Here is the paragraph.
Most dealers are still looking to buy a wide range of material for their clients with the number one criteria being that the coins must be at least average or above average for the grade. This is important because their customers are becoming increasingly educated in numismatics and in turn more picky in regards to the quality they will buy. Strong demand is focused on coins that are problem-free and possess nice eye appeal. Strike and originality are also extremely important as today's buyers look to add somenice specimens to their collections. Early coinage that was minted in the years prior to 1840 remains in serious demand. Active buyers are looking for most dates and denominations as they know that these rarities command serious attention no matter what market conditions exist. Bids have been steadily increasing for Flowing Hair and Bust coinage and expect this trend to continue. Dealers still believe that many of these coins represent an excellent value at current levels with plenty of room left. However the supply is quickly drying up and the pickings are slim at the moment. For now, dealers hope to have some success at public auction and on the bourse at the MidAmerica Coin Expo in Rosemont next week.