I'm making wedding invitations for a dear friend. We decided we liked the idea of pocketfolds (see the link above to cards & pockets) but they were out of her budget. I did some playing with a scrap piece of paper and figured out how to make the pocketfolds ourselves for about 25 cents per pocketfold versus the $1.50 per pocketfold if we bought them.
I figured out where to cut & score & fold, then bought a sheet of 19"x25" artist paper from Hobby Lobby for $1.99 a sheet. You can get it in many colors and textures. It'll be a lot of cutting, scoring, folding and gluing. We're planning on having a glue & assembly party with a lot of helpers
There's lots of tutorials online from brides and The Knot has been a great source of DIY wedding stationary stuffs.