Well, since you didn't give exact parts and speeds, I can only guesstimate prices.
PII X4 965 is ~$85 new. Depending on overclocking and stepping it would generally go for $50-70 used with $70 being rare. Random mobo that you didn't ID, probably $30-50. 16GB RAM of unknown speed, probably 1333MHz, $50-70 depending on model and speed of the RAM. 5770, $40-70, $70 on a good day. Used 1TB 7200RPM HDD, $50-60. Could be lower if it's an older unreliable drive. No name PSU, $5-10. ODD, $5-10. Unknown Antec case, who knows.
$400 would be generous for that computer.