Oooh, yeah-- homemade costuming does seem like a lost art-- I think that's one of the reasons Martha Stewart's Halloween edition of 'Living' (the magazine) is so cool; she has lots of really interesting ideas for homemade costumes.
Something else that we get a lot of questions about on the forum are how to carve pumpkins-- what tools to use, where to find good (free) patterns, how to make a pumpkin pattern.
Cheap decorating ideas-- for parties and homes (in general) are also high on the lists of things people like to hear about. We often get "how should I decorate" questions. I think it's important to let people know that there are other Halloween colours besides black and orange out there-- Green, purple, and red are also "Halloween". Plus, you don't just have to stick with black cats, pumpkins and ghosts. There are a wide variety of Halloween themes out there that can vary depending on what you want to do with your party. Rather than doing a broad theme of "Halloween", it can help decide how to decorate by picking a more specific theme such as "Vampires" or "Witches".