The meaning of "rack" depends on the context. Here are the two most common interpretations:
Slang for money: In slang, particularly hip-hop culture, "rack" refers to $1,000. So, in this context, a rack would be $1,000.
Physical structure: A rack can also refer to a physical structure used for holding or storing items. The price of a rack in this sense would vary greatly depending on the size, material, and purpose of the rack. For example, a simple metal storage rack for a garage would cost much less than a specialized server rack used in a data center.