michael d:
Lee Valley is a great suggestion, even if they are Canadian ;-)
Don't miss out on my favorite toy store, Rockler. Lee Valley's service is awesome, too!
A very good source is "Veneering & Inlay," by Jonathan Benson (Fox Chapel Pub., 2008).
You can rough cut with a blade on a cutting surface, scissors, or my fave, a rotary scissors (looks just like a pizza wheel).
May find them @ some woodworking places/sites, but any decent sewing/fabric store would carry a good OLFA brand one.