Hearthpwn

My collection stats:

Classic: 455 / 709
Witchwood: 89 / 247
Boomsday: 79 / 247
Rastakhan: 111/247
Shadows: 149 / 247

I bought the 50 x Shadows bundle
Lunar Year Bundle (10 x WW, 10 x Boom, 10 x Rasta)
Welcome Bundle (30 x Classic)

Not sure where to invest, if at all. 
I have 2500 dust

Sell your account for bitcoins.

Kappa

Do not craft anything until the end of the month and the meta solidifies. Use this time to experiment with decks using the cards you have. Everyone is either a Boom Warrior, Murloc Shaman, or Token Druid right now. Be something better!

Buy all the RoS, craft the needed legendaries and epics from other sets. Thats the most efficient long-term investment.  After that, hoard gold to the next expansion. It should be around 8k, which is pretty good.

Thanks for the information!

Depends if you are a collector. If you want the entire set or at least most of it, buy lots of packs. If you like getting packs though arena, save about 2k gold for arena. Remember to have 2k gold available for the miniset in roughly 2 months though.

If you are not a collector, only buy packs until you have all rares. Then, just craft the good epics and legendaries, or the ones you find interesting and unique if you can afford the luxury.