how i think of it - price is set by limit orders, price movement is caused by marketable orders (limit orders to sell at bid and buy at ask are market orders)
offer it at 4.60 and the spread will narrow to .05. You can eliminate the spread by offering it at 4.55, but I doubt that will last long. If you like tight spreads try bidding 4.73 and see what happens.
Even baseball cards do have a spread...and IPOs...and well...check it out...crazy as it seems: http://www.etopps.com/