Kim, I can give you a little of what I know, I used it for years but now in Australia a pack of 20 is up around $180AU!!! There are TWO processes to do with Polaroid. (I refer to a box of 20 single polaroids, 5x4 size, which are put into a special holder one at a time) 1) Image Transfer 2) Emulsion Transfer
If you don't have a 5x4 camera, an alternative is to use what they call a "daylab" which will print your 35mm slides onto one of these polaroids, but also using the special 5x4 holder. The daylab is not cheap but the polaroid holders can usually be found second hand for not so much money.
I could write a book on this subject, as all users probably could, so I suggest you look into some books, there are a few available, also I'm sure there'd be something online somewhere.
The polaroid Image/Emulsion Transfers are one of those processes which takes a lot of testing/failures etc and can be painful to the hip pocket if you lack patience. Hope I have (not?) put you off!!