None of your links work.
This is about the cheapest your going to get with a 5770 and 4GB ddr3 ram.
If you had to go cheaper then switch the 5770 for a 4850, won't lose much performance. The 4850 is one step down from the 5770.
an LCD monitor with those specs all under $500 is absolutely impossible. This is the cheapest you can get with an LCD.