Does CSGO coupon even exist?

It doesn't.

There's no need. If Valve wants it to be on sale, they'll just put it on sale.

You just missed summer sale where it had that discount. Resellers might sell it bit more expensive soon

I actually bought CSGO on 75% off on the times of the bravo campaing (bought CSGO complete for like 6$? or something like that)

But thats not going to happen again since CSGO began to drop expensive items.

wow, no coupon for csgo, but a 50% coupon for Dark Souls 2 xD

Yes, it is. I have -75%. But not for you.

There are coupons for other Valve games but not for this one.

Could be discounted on 21 August,the day when the game was releasead.
I think last year was discounted but I don't remember for sure...

It doesn't go lower than 50% anymore on Steam

i bought in 2013 sales on 75%

:3 and earned more than 60 dollars to the date only drops

Good news, bad news.
Bad news: Valve promised to never make it cheaper than 50%, as a way to fight cheaters who first get ban, then rebuy dozen new copies to cheat (which, in the end, is only making Valve richer, as cheaters will buy those accounts anyway, even full price).
Hypothetically good news: there's CSGO birthday in like 3 weeks AND right along birthday there's big CSGO Tournament (ESL Cologne). I would be really surprised to not see CSGO on sale at least for one day then.

Note: if you'd sell your all cards, emots and backgrounds you'd get over $6 to your Steam Wallet - maybe that will help getting that CSGO?

I bought cs:go in the exploration sale last year, maybe they'll do it again :o http://store.steampowered.com/news/15081/