Short answer: It depends...
I am unsure about the going rate of used Macs is where you are located, but for the US, that seems a really expensive for an older Mac that you are unsure if it works. Maybe if it was a rare, but in this case, probably not.
I would try to get it booted first, look at the specs, then make a decision.
Swapping the HDD for a SSD is pretty easy with this model, so that is a plus. I think El Capitan is the newest OS for it, at least officially.
I also wouldn't use this as my primary Mac, as it is pretty old, but for you, depending on what your intentions are for it, it might be okay for a primary Mac.
What do you plan on doing with it?
[automerge]1583905783[/automerge]
I would try to get it booted first, look at the specs, then make a decision.
Oh yeah, I forgot to ask if you think that the seller would allow your to test it with a bootable external drive, just to see if it boots and if it has any issues.
You can just bring your own.