As of today, Buy It Now on ebay is up to $159 for a set, so right now my prospecting is looking ok.
I'm not doing this to be a dick, but I did want to point this out: Mox Opal is available for
$18.00 on Naked Yeti Games. So, as I predicted, the price has come down from its initial pre-order cost. Since all the best cards in SoM are Rare and Mythic, there'll be a ton of packs opened to get them and a ton of sets redeemed online. And there's a four month lull between sets, so there will be lots of people drafting SoM for an extended period of time. So, the price will likely slide further. I think they'll be get-able for $15.00 before MBS comes out.
Peace,
-Troy
EDIT: Update- Channelfireball now has these for
less than 15 dollars. Now, I'm almost wondering if they'll be around $10 by February. Wow, that would be a steep decline.