Super Hero Halloween
Halloween costumes are expensive, especially ones officially certified Marvel, DC, etc. If you're on a budget but you're still feeling the "earth's mightiest" kind of vibe, try out some of these low-cost costume alternatives:
Okay okay, just kidding. These are called "low budget xmen" from the blog The Awesomer. There are four total, but these are my personal favorites.
In all seriousness you can still have your super hero costumes. Several different stores and websites carry tshirts resembling the top of superhero costumes.
You can also buy or make props for added effect, and if you're having a hard time finding the right color purple boot or something, here's a tutorial on how to make boots from duct tape: