Stll good for gaming: I7 3770 and 16GB RAM
No longer good for gaming: GTX660
Neutral: 128GB is ok but I would recommend getting something at least 250GB
Neutral: 1TB HDD
Basically, that GTX660 is quite useless and you should definitely deduct it from the price.
Note: I hate getting and selling second-handed SSD and HDD. I would take these out of the price too.
hmm..you plan to buy that rig I7 3770+GTX660 +128GB SSD+1 TB HDD for USD400?
Does it comes with everything? e.g. Windows, optical drive, etc., if yes, USD400 might be at the limit for that second handed rig. Can you bargain to make it max USD300-350?
If it comes even with peripherals such as a monitor, keyboard, etc. I would pay that USD400.
USD150 as upgrade? I would spend a...