How much is my old PC worth as a full unit?

[Vakna]

So I just got a new tower, complete with all the internal hardware and my old base unit is sitting collecting dust. I thought I might as well sell it and treat myself to a game shopping spree with the funds. Not sure how much the thing is worth though at this point. Here's the specs;

Windows 7 64-bit home premium installed with free version of Microsoft Office.
500GB basic HDD (came with the case)
Intel Core i5-2320 3Ghz Processor (came with the case)
8GB Adata XPG Gaming V2.0 1866Mhz RAM (added later cost £44.99 brand new)
Gigabyte GTX 550ti OC 1GB GPU (added later cost £89.99 brand new, version with 2 fans on it)
Coolermaster Elite Power Supply 500W (added later cost £27.49 brand new, runs very quietly)

It's just the base unit, so no monitor, keyboard or mouse included (though I do have a crappy basic keyboard/mouse I can throw in that I just keep around for spares), the rig itself was purchased in 2012 and I used it for 3 years for mostly gaming, playing world of warcraft and various other titles. Will run mid range games like WoW really well but struggles on the modern releases. I played Dragon Age: Inquisition on it but only on lowest settings at like 20 fps. Hard Drive seems to have seen better days as it now takes about double the time to boot up than it did when I first got it (about 1m30s from cold boot, and hangs on a black screen for about a minute longer while loading up the desktop graphics). There is also no build in cooling fans on the case, only on the internal components so it does run quite hot while gaming, about 70c on the GPU and CPU while raiding in WoW and about 75c on both while playing DA:I. I was also considering taking the RAM out of the unit and adding it onto the new ones I got in my current tower, and putting a basic 4GB stick I have laying around in the old PC before selling, I don't think most people care enough about RAM to pay extra for a premium set, should I do this or leave it in?

Also, I live in the UK so a value in GBP would be preferred but I can easily translate from USD if anyone gives me a suggestion in that. I'm also open to selling it off as separate parts if you think I'd get more for it that way.

[Vash The Stampede]

Generally worth more in pieces that as a whole unit, but it's more work to sell each piece. Honestly the hardware in that machine isn't exactly worth it for anyone to spend money on. You could just use it as a HTPC or make it into a NAS. That's what I would do.

[Butler to Baby Sloths]

You'll be lucky to get 150 for it. A computer that old isn't really worth anything at all.

[Master Guns]

It's not worth anything sadly. Those parts are ancient.

[Aleksej89]

Yea the parts are kinda old, you best try talking to the local PC repair shops - they might be interested in certain pieces.

[Deleted]

What duke said, not worth to sell, make it storage server.