$2000 mining rig

I have acquired $2000 that I plan on building a LTC mining rig with and i wondered what some of the best options are for this price range. I have done some research but I cant really find any good info about what GPU's to use. I originally considered buying an A4 Dominator but that doesn't seem to be a good as a choice as building something. What would some good GPU's be? I am new to mining and would appreciate any responses. Thanks