Hi, I saw this posted twice so I have deleted the other post so that all your replies can be consolidated on this thread. There is an article about what to do if you have failed here:
www.project-management-prepcast.com/failed-pmp-exam
You don't necessarily need to buy anything else, just keep going and make sure you've fully revised all the topics and are prepared to answer the exam questions - simulator practice is the top tip, one that we hear time and time again, so keep doing those mock exams and track your scores. Soon you'll see the results trending upwards. Good luck on your next attempt.