Should I buy a sightstone when jungling on almost any champ?

I was just playing a game, when I was thinking, "Man, we could use some extra visions since the 3 wards from support isn't doing quite enough." Sure, one of my friends I was duoing with had the upgraded trinket, but I still feel like that quite wasn't enough.

Now real quick I'm just gonna mention that whenever I play a support or tank jungler I usually get sightstone since I'm not really going for damage anyways.

And now I'm watching OGN and I noticed that a Pantheon and Rengar both have sightstones. Now I know, well it is pro scene but I was wondering if it is worth it to invest that extra gold and inventory slot so I could always have wards available. Especially since I constantly have those games where I reach full build and have a sweeper and the rest of my team (sometimes not even my supports gets a sweeper or sightstone, let alone buy wards) rarely upgrades or even use trinkets to get vision.

So would it be worth it to potentially always have that extra vision? I mean, I've had plenty games where I've thought "Hmm, what should I get last item" and usually just say fuck it and get GA even if I don't need it.

TL;DR: Should I buy a sightstone on every champ whenever I jungle, even champs like or only on "support" junglers and just hope that late game my team can cover the warding while I have a sweeper.