At the local Hobby Lobby, I recently came across large chipboard block letters. While they were on a scrapbooking aisle, my mind instantly went to the decoration of my home.
The letters come in a few fonts and hover right around the $1 price range. At anywhere from 3 1/2" to 8" tall, they are an extraordinarily cheap alternative to wood or metal options. Create your own sign and choose a look. I could see painting these a glossy bold color for a striking accent or maybe a matte black for a wrought iron appearance. See all available options at Hobby Lobby.
Seems I'm not the only one to equate these letters to home decor instead of scrapbooking. At the blog Frame Fanatic, an "EAT" sign was made using this exact product (pictured below).
Images: Hobby Lobby, Frame Fanatic

White Enamel Flatwa...
I did something similar to this by covering a cardboard C from JoAnn with scrapbook paper. They have some really, really large letters and I've been thinking about picking a couple more up.
A perfect excuse to enjoy our new married initials and buy cute scrapbook paper!
I know a lot of mosaicists that mosaic them for kids rooms and such.
Strauss in the Frankfurter Allee in Berlin has 3D lettering on sale now (±30cm/1ft). strauss-innovation.de