Unfortunately your roommate is right, paying full retail for that snake just improves Petco's bottom line and encourages them to continue to keep snakes in bad conditions. That boa looks deplorable - I would be embarrassed to have a snake in that condition unless there was some underlying factor like an illness. I certainly would never offer it up for sale.
You can contact Petco corporate and complain here: http://www.petco.com/content/contact...tactstores#top