Buying used i7 6700

[bubyy]

Hello guys.

I was wondering if I should buy an used i7 6700 for 155€. The seller bought it 2 years ago. He doesn't have the warranty nor the bill. I'm currently using a G4400. I don't want to waste so much more money on a new i5 7500 (196€) when I can get the i7 for only 155€. 
How do I trust the seller?

Thanks.

[Princess Luna]

Buy from a place with a good return policy?

[nick name]

You haven't told us anything about the seller or the through whom the seller operates. Gotta know something before we can give any guidance on whether you can trust the seller. 

[bubyy]

5 minutes ago, Princess Cadence said:

Buy from a place with a good return policy?

It's on a page where people sell stuff themselves. Not like e-bay. I don't know if I explained that correctly. I think it's something like craigslist in the US.

[Ground]

I've bought about 90 used CPUs way older then that and hadn't had a single one that didn't work. If the seller appears trustworthy it should be fine

[nick name]

I bought an entire used PC on Craigslist but had the opportunity to see the PC running at the seller's home. Contact the seller and see what they and you are comfortable with. Communication is a huge factor in deciding if someone is trustworthy on sites that don't give separate guarantees. If you feel comfortable with how they interact with you then move forward. If you don't feel everything is on the up-and-up then find another seller.