How much $ should i sell my pc

Solution
Depends where you live, if USA then.
I5 4570 100$-130$
750Ti 90$-110$
Ram depends from speed and is it single or dual.
HDD well 30$ if over 1 year old (i paid new 20$ Toshiba).
PSU well which brand, 400W isn't eunogh (if random brand i count is as useless).
cooler master silencio 352 50$-ish
Total:250$ that would be similar to real price. But you can bump up price up or down by 5-10% margain.
Depends where you live, if USA then.
I5 4570 100$-130$
750Ti 90$-110$
Ram depends from speed and is it single or dual.
HDD well 30$ if over 1 year old (i paid new 20$ Toshiba).
PSU well which brand, 400W isn't eunogh (if random brand i count is as useless).
cooler master silencio 352 50$-ish
Total:250$ that would be similar to real price. But you can bump up price up or down by 5-10% margain.
 
Solution
$250-$300 would be a more realistic price as complete since you can find OEM's without a GPU with the same states for $175-$200.

Parting out
CPU/MB/RAM Combo $150
GPU 750 ti "2gb" not "1gb" $75-$90
PSU/HDD/Case... maybe $30-$40 complete.