Don’t do that. “Wild packs” are terrible. They can contain cards from any expansion, and most of those cards are unplayable trash. TBH, you might want to buy up to 10 for your guaranteed legendary (if you didn’t already get it), but even that isn’t likely to change the fact that most cards you will get are unplayable due to power creep.
If you want a number of cards from a particular wild expansion, then buying packs from that set might be worthwhile, especially if you don’t yet have the guaranteed 10-pack legendary.
But, overall, if you want wild cards, its best to just craft them.
There is only 1 Demon Hunter card in legacy that is craftable (uncraftable cards cannot be pulled from packs). That is Kor’vas Bloodthorn.
If you want that card, then realistically you need to craft it. For some reason all the other DH legacy cards are uncraftable. These cards have “special unlock requirements” which means you have to do something very specific to unlock them, and its possible that the task (and therefore the card) may be no longer available.
Most of the DK cards are craftable, which means they can be found in “wild packs”. However, if you want these, you’re probably still better off just crafting them.
However, most of these cards are unplayable in wild format, so crafting them is probably a waste of dust anyway.
Remember also, that if a card ever rotates into core, you will get free (temporary) core versions of those cards, so you won’t need to craft them.
What I would do is make a list of which cards you want, and work out how much it would cost to craft them. However, I wouldn’t expect it to be worth the dust.