72 Week US rotation Americlerkship?

Think about doing a 52- 72 week rotation with Americlerkship in about two years, (basically my last two years of medical school clerkship with them, but they have been pushing to sign up ASAP (like right now), and they tell me space fills up very quickly. If I want back to back, I have to sign up 1 - 2 years in advance to get green book rotation. (My question is: is this just their usually sells pitch, I should take with a grain of salt or I have to COMMITTEE myself to a company this soon. My plan is to get green book back to back rotation at least for core electives, (fill up my last two years of med school clerkship, keep in mind the ultimate goal is to get into a US Internal Med Residency or Surgery hopefully save some money along the way (they charges $499 a week.)

My sedond question is: should I do alll my rotation in green book? the cost does concerns me.