This one is easy. Just go and buy one. :-D
But - read this first:
How to Choose a Polaroid Camera?
How to Get Started With Instant Photography?
Five things you should know about Polaroid Camera
The 21st century Polaroid: Real-life Instagram camera lets you print out a retro postcards
I am also interested in Instagram Photo Printer. Makes a "polaroid camera" of your iPhone or Android :-)