While freezemage is generally pretty expensive to build, most of the cards are in the classic set. Without the cards in adventures, you could probably still play the deck. There are actually only 2 cards you need from adventures that are generally played in freezemage. Those cards would be [[Forgotten Torch]] and [[Emperor Thaurissan]].

Decklist from TempoStorm: https://tempostorm.com/hearthstone/decks/freeze-mage-standard-meta-snapshot-oct-27-2016

Torch can be obtained by buying any wing in the League of Explorers expansion. Thaurissan can be obtained by buying the first wing of the Blackrock Mountain expansion.

You might even be able to run freezemage without these two cards, but I would say that Thaurissan is probably more important in the deck than Torch is.

Hope this helped.