If you want a low-cost way to learn how to use the camera, then Polaroid/Fuji instant film is
not the way to go.
Freestyle sells some pretty cheap EDU Ultra 400 for $33 for 50 sheets. The stuff, however, has horrible reciprocity failure and is only suitable for well lit subjects - figure 1/25th of a second shutter speed or faster to stay out of danger with losing shadow detail. You can process it in HC110 in a tray in 3 1/2 minutes, a minute or so in rapid fix and there's your negative. If you are really into 'instant' results then you can process the negative in Dektol and make a contact print with a wet negative (you can even do it in the trunk of your car
http://www.weegee.org/).
As others have mentioned, paper negatives are another easy entry with very low costs.