"Drummer's Brain" joke

A customer walks into the brand new store downtown that sells brains. There are three glass cases, each containing a nice wet quivering gray brain.

The first one says "SCIENTIST", and it costs $100.

The second says "ELECTRICIAN" and costs $1000.

The third says "DRUMMER" and costs $10, 000.

The customer is confused, and questions the salesperson.
"I don't get it... why would I want a drummer's brain for $10, 000 when I can get an scientist's brain for $100?".
The salesman replied, "Because, it's never been used."