Getting 7770, which PSU would be the best

None of them. Get one from corsair/ seasonic/ enermax.

You see how the 80plus logo in the picture of the 500W Chieftech looks odd? They are lying.

Tell us where you live and we can link a decent PSU available in your country.

Bosnia and Herzegovina - shitty triangly country. Didn't see any corsair/thermaletake/seasonic/anything_good in the stores though.

Can you not buy online even from another country?

Dunno if its worth that much since I'll be running this low powered rig, and i do not intend to upgrade it at all - think ill just buy a new pc in 2-3 years since this one is pretty outdated with the 775 lga E5300. I just want something to be able to game a bit until i can afford a decent pc.
So one of these 3 PSUs should be able to do a e5300 + 7770 imo.

Yes, but you will be looking at much higher costs 2-3 years from now if one of those PSU's goes and destroys everything else with it. You might get lucky though.

Well assuming these PSUs are kinda mid tier, and that i won't be using even 50% of their power I think I should be on the safe side. Heard that both Fortron and Chieftec are pretty solid, unlike my current CODEGEN which blows up all the time.

Well I have been running a FSP power supply for the nearly 3 years(24/7) without issues(300 watts i5 750 with a 5770   now it has a GTX 650 ti). I do not think they are THAT bad.

a 7770 is very power friendly to be honest.

I have no experience with chieftec or who they use for an OEM, but they seem to have lots of power.

The actual problem with CHEAP power supplies is most time they have all the power on the 3.3 and 5 volt lines. Then when you try to hit the 12 volt lines hard they fail.

I have seen one FSP power supply fail ever and it just shut off and never went on again. No hardware damage no fireworks, just off.

As Nuke said, the 7770 is a fairly low powered card. My 7750 doesn't even need external power from the PSU but I think the 7770's need 1 six pin.

Check my online store list:
http://www.tomshardware.com/forum/358998-31-worldwide-o...

Here is one.... but they may not be secure. Careful about using them.
http://www.kimtec.ba/

I see that this store in Bulgaria has Seasonic and Corsair
http://www.speedcomputers.biz/product/corsair-builder-s...

And in Serbia there are many stores.... this one carries Seasonic PSUs
http://www.emmi.rs/napajanja-i-dodatni-ventilatori-napa...