You can get a really basic 15" LCD for around $180. NewEgg.com is a good place to look.
This is the cheapest one there - $179.99 including shipping. I'd really recommend trying to stretch the budget just a little and get a 17" one though. The cheapest 17" LCDs are just a little over $200, and they offer almost 70% more pixels than a 15" one (1280x1024 resolution vs. 1024x768).
Hell, I just checked and it looks like NewEgg's running a deal on a 17" LCD for $202 shipped, right
here. It's probably not the greatest LCD, but I have used a few super-cheap brands before and none of them have been especially bad. $202 shipped is an awesome deal.