How much is my PC worth

Solution
It's only worth what someone is willing to pay. It's hard to put a set price on custom builds because no two are exactly alike. But a shot in the dark I'd say in the ballpark of $300 (USD assuming you are in the US). No overclocking ability, and only one stick of 8GB memory (making it more expensive for someone wanting a 16GB upgrade and needing to buy a 2x8GB DDR3 kit). Your video card is the single most valuable component. I see 4GB 960s selling on eBay for between $150-$180.

You might get more money parting it out (generally a CPU and motherboard combo sell pretty well together on the used market). However, doing that has risks as well. You may be stuck with some components that don't sell. Of course this all depends on where you...
It's only worth what someone is willing to pay. It's hard to put a set price on custom builds because no two are exactly alike. But a shot in the dark I'd say in the ballpark of $300 (USD assuming you are in the US). No overclocking ability, and only one stick of 8GB memory (making it more expensive for someone wanting a 16GB upgrade and needing to buy a 2x8GB DDR3 kit). Your video card is the single most valuable component. I see 4GB 960s selling on eBay for between $150-$180.

You might get more money parting it out (generally a CPU and motherboard combo sell pretty well together on the used market). However, doing that has risks as well. You may be stuck with some components that don't sell. Of course this all depends on where you live and the market for used PC parts. I live in a greater suburban metro area of a major city in America (Atlanta). There is no shortage of Craig's List buyers for my used PC components. Been doing it for 10+ years.

I do however keep some older components around that are swap-able no matter the chipset like the PSU and GPU from a previous outdated build. I like to have some extra components around in the event I need to troubleshoot a new build and make sure a new build component isn't dead.
 
Solution
Rule of Thumb - Take your build cost and then subtract 10% .... then 5% for each month of age for 6 months (60% value at this point) ... then 10% for every 6 months thereafter.

0.5 year old - 60% of build cost
1.0 - 50%
1.5 - 40%
2.0 - 30%
2.5 - 20%
3.0 - 10%

That build has gotta be about 3 years old in which case, it's worth abut 10% of what ya paid for it new.