I tried numerous DIY solutions, from a painted on wall, to a spandex screen. I decided to go halfway and get professional screen material and make the frame myself. I will never go back. You can get DIY Centerstage XD material from Seymour AV. It's acoustically transparent so you can put your speakers behind the screen to make it look more aesthetically pleasing (if you have a wife, I'm sure she'll appreciate it) as well as having the sound come from where its supposed to be on-screen. Chris is super helpful and will help you get what you need to get started. And yes, I agree that doing something yourself is much more satisfying than buying it pre-made.
I thought I'd edit this and say that the screen material isn't exactly inexpensive per se, but your screen will most certainly outlast your projector. A favourite saying of mine, although I don't always adhere to it, is "be lazy, do things right the first time."