A while ago my brother suggested to me that maybe the optimal line of play for a 'free to play' constructed player would be to flat out ignore some of the classes. Thus far I've been only disenchanting excess cards but I could just blow up every card for a class I'm unlikely to play in constructed like hunter. Certainly with the new information that I'm going to want constructed decks for 3 or 4 classes it certainly seemed like investigating the value I could earn by sacrificing 4 or 5 of the 9 classes seemed reasonable.
I've had a spreadsheet under construction for a while now with every card list and how many I owned to make it easier to track what cards I still needed for specific decks. It was a simple matter to modify that sheet to take into account the value for blowing cards up and then break things down by class to see where I stood.
For reference I have specced out a a few decks I'm potentially interested in and they mostly cost in the neighbourhood of 5500 to 6000 extra dust to make.
Now, if someone were to step into things with no cards but infinite dust, how much dust would they need to make all the cards? Each class currently has cards that cost a total of 9440 dust to make. The neutral cards cost 90160 dust. All told it would run you 175120 dust to make all the cards. I've averaged about 100 dust per arena run with my ~67% win percentage so I would need to draft 1751 times to craft all the cards. (Fortunately most of that dust is generated by blowing up cards from packs and I can just keep 2 of each... But even then, the relevant cards are only worth 4 times the disenchant cost so it's still a silly number of drafts to get all the cards.) I could also buy packs with gold, and I do average 125 gold per draft.
Anyway, those are just some numbers with no real importance on my current dilemna. The question that actually stands is what I could get by blowing up all my cards of a class. Could I get the 18k dust I need to make 3 more decks? (Actually less than that since all 3 decks run The Black Knight which runs 1600 dust to make alone.)
The answer is a resounding no. If I were to blow up every single card I owned I'd only get 5850 dust out of it. And that includes blowing up Dr Boom for only 400 dust when he also goes in one of those decks! Choosing to sacrifice all of my druid cards would only get me 135 dust! I could get almost 700 out of my mage cards, but I'm using many of those in my only deck! Heck, I have 750 dust on hand as it is, and I've spent 3200 making cards already.
So while sacrificing a class or two is an interesting idea, it actually isn't very useful for me. It wouldn't get me any of the decks I'd want, and it would certainly set me way back in the long run. You never know when I'd suddenly want to play a shaman deck and be sad that I didn't own any shaman cards at all. It would also take a lot of clicking to blow up all those cards (there's a button to automatically blow up all the excess ones).
There is the option of manually picking out the epics and legendaries I own that really suck and blowing those up. I have a Bolvar Fordragon card, for example, and I can't imagine ever putting him in a deck. But that's one card, worth only 400 dust.
Realistically there are only three options that I see to actually get a bunch of cards. Pay a bunch of money, draft a ton for dust, or spend gold on packs instead of on drafting. (Or go super infinite on drafting...) I've actually been hitting the gold earned cap in ranked play every day this week and while that only gives one pack it is a pack for a set I can't win in draft.
Touching on that last point a little... I now own every common in GvG and 93% of the rares. By contrast I own 27% of the commons and 10% of the rares in the classic set. So I actually do think I need to buy a bunch of classic packs in some way.
I don't want to spend money on packs at this point, so I think my plan is to keep playing a lot of constructed and spend some of that gold on packs and some of it on drafting.