How much does this cost to the nearest dollar?

Atomic Market 2 1/4 Inch 2.25 Purple Ball PS/2 PCB Connector Arcade Trackball Mouse for Jamma MAME Arcade
Manufactured by Atomic MarketPurple trackball, smooth rolling Operates just like a standard computer mouse PS/2 plug and quick connects, will work with any computer through its PS/2 connection. Long lasting, low power trackball. Purple trackball, smooth rolling Operates just like a standard computer mouse PS/2 plug and quick connects, will work with any computer through its PS/2 connection. Long lasting, low power trackball. Dimensions 5.5 x 5.5 x 2 inches, Weight 8 ounces, model number Rank Computer Trackballs 178, Is Discontinued No, Available August 15, 

Price is $51.00

Price: $50.75