Since you're on a budget, the most budget consciense wind screens are home made. I've done this before and they worked great.
Just go to your JoAnne Fabric store and buy some furniture foam...or craft foam...whatever you wanna call it. The stuff I got was about 4 inches thick. Then wait until the wife is outta the house and use your electric carving knife to whittle a pair of screens out of the foam.
For the hole, I just kinda plucked away at the center with an exacto knife. The resulting hole wasn't a perfect circle, but it doesn't need to be. Yeah, these were homely as can be, but Stevie Ray Vaughan didn't seem to mind playing a flea bitten homely guitar, so what the hell?
Before someone chimes in with doubts about the foam being too dense or not dense enough, it ain't an issue...these work just fine.
If looks is an issue for you, just throw some homemade dead rats over them and you never know either the rats or the screens are homemade.