As counterintuitive as this is, the process being one long line of virtual hands being held out, there is no charge for the score report no matter how many you need. They aren't paper reports anyway--you just let them know which schools and they download the report. After you submit your AMCAS, you can see online who has downloaded and on what date and at what time.
If you apply to non-AMCAS schools you have to have one sent, but there aren't many of them left now that NYU and Columbia have finally caved (unless you're in Texas). BTW, the AMCAS site still lists both those schools without the AMCAS designation, but as of this cycle they are both AMCAS schools.