Wifi With Higer Range

Good day guys, I know about wifi very well it range of connection is less than 500m,but i was told that  it is posible to extend this range to somthing like 5km! without any other equipment in the reciving end other than my computer. How far is this one true?Then what type of equipmwents will be at the base station to give such a range?
If i will buld such it may cost like how much.
alaran@dcmail.com