I like Coldlight, but the only problem is that you really won't be milling them without Mukkla (I don't have him :< ) or Prep+Vanish+Leeroy (a combo I have enjoyed abusing).
What's more important than Mukkla or Auctioneers or even Preparation is Azure Drake, which I highly recommend you save up for. Azure Drake is just that good of a card that it's used in a lot of decks. The value you get out of it is just insane, and even if it dies the turn you put it down, you still draw a card. Not to mention it's great for comboing with other spells that Miracle Rogue, Mage, etc carry. If you do have spare dust, I would at least craft one preparation so that you can abuse Prep+Vanish+Leeroy (This is a turn 7 play that guarantees at least 12 damage and 2 worthless 1/1s put into their hand, 18 damage and 4 1/1s if you have Shadowstep).
But yeah, I would look at investing Dust into Azure Dragon for sure just because it's that good of a card.