female ball python for sale

I have been reading up on determining the sex of ball pythons, and as far as I can tell, she is a female, however, I am not absolutely positive... I live near Sacramento, California and I am only selling this snake because my mom will no longer let me keep him in her house. She is about four years old and a little over four feet long, I have seen similar snakes sell on the internet, I am asking 200 for just the snake, or 300 for the vivarium, water dish, hiding log, heat pad, and climbing stick... please email me at D_M_A_C@hotmail.com for inquiries.
PS she is a great feeder.