What is my PC worth?

Google the price of the parts.

use pcpartpicker.com

granted that will give you a price of new parts but it will give you an idea of what your pc would cost new.

if someone gonna pay you 200-300$ definitely, it's not bad, GPU and other stuff are good, but the thing is old...you have the 2TB HDD and SSD, so someone may buy it not to use it, but to take the parts. For a 2tb HDD, 128Gb SSD, good case, and good cooler, 200$ is definitely good deal.

But is better if you buy a new one, and just use your SSD, HDD, other parts like fans, cooler or case you may have, so you don't have to buy them.

In my opinion you can easily sell it for 200+, even 300 is a good deal.

$200-300 sounds about right.

I'd try and sell it for around $280, then assuming people will bid around $250. You'd be lucky to sell it at more than that.

Your motherboard is heavily outdated, will not support ANY new CPU(So even using this for new parts would junk)
AMD Phenom II X2 555 3.2 (Garbage as well will bottleneck any new GPU, meaning this won't support any high end GPU's from the past 2ish years)
8GB RAM - I'll just guess and say its DDR3-1333, which is still viable, so these have some value ($50)
AMD Radeon HD 4890, Once again outdated, at most I'd give this $20 value
128GB SSD- This could still be worth some money, depending on how many times you defragged it, it can run as perfectly new. $90~ if mint condition.
2TB HDD- No new changes in HDD's for the past couple of years, aside from size. Still worth $80ish

Overall, its a great deal, sell it to the guy and run, if you can try to take out your SSD and then sell it to him. Guy is obviously an amateur.
Went to go check prices for a HD4890 USED, the guy below me was right its about $40....GG worth slightly more then I thought. Though, personally I wouldn't buy a GPU thats been used for 5ish years....
$20 difference == Spouting Crap
GG #PCMASTERRACE is to intensive.

Stop judging your PC by his parts! They don't have to measure themselves by your artificial social standarts! #AllPCsAreBeatiful #StopOpression

How much my PC is worth:

AMD 5000+, GF8800GT 512MB, 4GB RAM :P :P :P