get a new good carbon frame and fork:
Planet X Pro Carbon Road Frameset | Planet X
with the remaining money of your budget, buy a used roadbike with a good groupset (shimano 105 or better) and which has good wheels .... get a decent saddle and good tyres/cables and you should have a very good bike for your budget
I'm seriously thinking of the planet x frame ... it only costs £299 (approx $430) and gets very good reviews ....