03 Vette trans is in the trans/axle. The engine drives thru a torque tube..Unless you are planning a transplant w/ independent rear, you will need a trans to bolt to the engine, such as a 4L60E, 6 speed. Both from the F body cars.
As for the $$ side.
Depends on the miles, what comes with, etc.
If all the ft accessories, PCM, foot pedal, tac module, harness], a low mile could be $2K...
If the guy selling it, doesn't know about the trans situation, he may not know where the engine really came from....