I agree with disykat--probably the most effective way is going to be to cut back severely on expenses. Little things add up to way more than we suspect! I'd also second the vote on selling some stuff on ebay, but you'd have to get on that really fast.
Another option might be to see if there is a plasma center in your area. We have one here that buys your plasma. Can't remember what they pay, I want to say about $30 per donation? Of course, they limit the amount you can donate, so you probably won't get your total $200 that way.
Depending how dire it is, you could also try selling bigger stuff through the classifieds. Extra furniture, tools, etc.