I assume you're wanting to put on a lycra suit? I've not personally tried a patch like that but my concern would be that it wouldn't stretch. I made a supes costume for halloween one year in college on the cheap; East bay base layer and briefs, XXL soccer socks to go over my shoes, and some generic red and yellow fabric from Micheal's for the cape and DIY emblem. Ended up looking pretty decent and was certainly good enough for a college Halloween party, though the emblem fabric didn't stretch the same as the shirt and pulled some of the stitching, doesn't look great if you're not drinking beer in a dimly lit house.
