i went to a "dress as your favorite rock star" party - what a blast! i was tina turner, escorted by bob dylan. we ran into so many celebrities - axl rose, stevie wonder, bob marley (w/ obligatory blunt), robert page, alanis morissette, blondie, so many, so much fun! janis brought her southern comfort. oh, it was so much fun. there wasn't really any food, just alcohol, so i guess it was like a regular old rock star party.
this is a great use of polaroids! i feel in love w/ transfers last year - they're great for a soft effect. i used them to make a dream journal for my alternative processes class. the thing i learned was that if they are for a book, it is best to to do the transfers before you bind the book, because you can't put a transfer on top of another one, or it starts to peel off.
The first place I would check is the local library. Often times they have very old editions of magazines and newspapers - old New York Times adds are great. As well as early Ladies Home Journals. The advertising is from another world. You can make copies, I like the graininess of a good ol black and white xerox machine, but if you are going for a cleaner look, color copies will cost ya a little more, but look more professional.
also, check for older botanical drawing books, these often have very elegant, pen and ink drawings of flowers in a victorian style. these be found again at a library, or at an antique book dealer. if the antique book shop is too expensive, oftentimes reproductions were made, although those will still cost you a pretty penny.
one time at Borders, i was lucky enough to come across a reproduction book of victorian food illustrations on clearance! you should see some of the pig and meat drawings there are.
some old cookbooks have nice victorian food drawings in them. christmas cards often have nice illustrations.
personally i take my decoupage art from anywhere I can find it - labels, wrappers, garbage, photocopies, books at yardsales, textbooks, scientific magazines, technical drawing books, children's books, art postcards - pretty much any scrap of paper I get my hands on. I especially love finding ambiguous handwritten notes, or drawings people have done.
It's nice because there aren't really any rules to it either, so it's impossible to ruin.