Looks like that’s how they are going to price the Diamond card from now on.
Option 1: opening 30 packs with one Diamond card guaranteed.
Option 2: open 30 packs for a random legendary guaranteed.
In option 2, people will still pay for it 3k gold, and they will usually end up one useless legendary and the dust of the rest duplicates will net you a purple card.
I think option 1 is not bad. So paying 3k without any dust bonus is kind of not too bad.
Yes it is the card is totally worth the 3k gold
It really depends on if you like the Diamond card.
The diamond finley that is coming looks ABSOLUTELY AMAZING. He spins around in a circle. That card would be worth 3k gold imo.
But Drekthar? Nah.
Depends on how often you’d use the card. If you use it a lot the card will pay for itself.
I just see it as the equivalent of a legendary, so if it was a legendary I didn’t already have and would actually use I would be ok with 3k gold, but since I already have him can’t say I am interested in it.
If you got it to spare and have interest in it then sure why not, treat yo self!
I would probably pay 1.5K gold for a normal legendary of my choice.
2K is probably too much (same cost of the miniset).
3K is out of the equation, but since the legendary is diamond I see why it costs that much.
Since diamond legendary are usually cards we already have or that we can obtain in a cheaper way, the price is good only if you think it’s good.
If you don’t care about cosmetics, you shouldn’t even think about buying it
I’m a big fan of cosmetics. I don’t believe this card is worth the $30 nor 3k gold.
Your calculation is flawed.
In average you should receive around 100 dust per pack. Yes, many will be worth 40, but there will be goldens, epics, multiple rares etc.
So if you are lucky (and you dont hit pitty timer), you receive legendary card + you receive as well another 2600 dust in average worth of cards. Which is another legendary for craft and 1000 dust on top of that.
The other layer is, that you can disenchant your 2-3 legendaries from packs in 1-2 years and get another one thanks to this. You will not be able to do it with diamond one (probably?).
So yeah, if it was less than 1600 gold for diamond card, which would be possible to dust once it rotates, I would (possibly) consider buying it. 3000 gold is way too steep, especially before expansion.
Definitely not worth it to me, something about diamond cards is just distinctly unappealing in my eyes(although I love golden cards, and have crafted around a dozen golden legendaries)
But if you like them, why not? I mean, if you’re f2p or otherwise struggling to purchase enough packs, then this is a no-brainer- obviously you’re going to spend your gold on packs.
But if you’re already comfortable purchasing the bundles you want and don’t need to spend the gold on packs, then gold had pretty much no value and it makes SENSE to spend it on fun cosmetics 
You just need to decide whether you need that 30 packs. If you don’t, and you like the diamond legendary, then get the diamond!