Upgrade to 6th gen or stick with what I have?

[Emalco]

Hello! Not too long ago I made a thread in which I asked for a good, not so expensive upgrade to my Intel G645 processor. My current setup would be:

Intel G645
Radeon 7850
4gb RAM
500GB disk.
600W power supply.

Now, I'd like to know, if it'd be better to get a new motherboard entirely with a 6th gen processor, or should I keep looking for one that runs on my motherboard? Which one would be better? I'm not really into running 2016 games at ultra or anything like that, I have enough running things at medium graphics. I can afford something like a core i3-6100, but I'd like to know if I'd be doing the right thing or not. Also, where I live, I can't get any of the online discounts or used parts, so price comparison would have to be full retail.

 

[ComputerSecurityGuy]

You'd be better off with an i5-3470 or similar, which for used prices costs about that much.

 

[Emalco]

Thanks for the answer! Yes, I've considered buying an used CPU, but sadly where I live, there are no reliable online sites where you can buy from trusted sellers, and you can't really trust someone else's words in a situation like this. What's the worst you could get from a used CPU, if the guy selling it shows you it's working and all? Having it die in a month? A year?