I'm looking at a few myself, but my budget is a bit higher than yours. In my research for a new TV, I did see an LG 42LM620T LED TV that would fit your budget. I don't have any experience with it myself, but it seems to be one of the cheaper 42" TVs that I have seen.
There are also Plasmas by both LG, Samsung and Panasonic to consider as well, which fall into your budget. Again, I have no experience with the current models, but I know the Panasonic's are good.
It really all depends on what you want from the TV. Does it need to be 3D, Smart TV, etc?