Don't worry: If you already spent cash on the game in beta, you'll get it back in gold to buy the same stuff again.
Hearthstone: Heroes of Warcraft is still in development, so players in the beta should know not to get too attached to rules or game mechanics or even their prized deck until the game comes out of beta and is finally released.
Case in point: All accounts are going to be wiped when a new patch hits some time soon. Developer Blizzard said that the wipe has been planned for awhile.
"We knew going into the beta that a number of cards were likely to emerge as overpowered and we also knew that we'd make significant adjustments to the reward system and overall game progression," the official site said. "So, as part of the effort to level the playing field and also prepare our players' accounts for the release version of our progression system, we made the decision to schedule a one-time wipe of all beta participant accounts."
That means all cards, gold, experience and levels, arcane dust, and medal ranking will become a fond memory. However, if you happened to spend some real cash for packs or arena entries, Blizzard has you covered. When the accounts come back up, players will get 100 gold for every pack purchased, and 150 gold for each arena run. So players will be able to buy back exactly what they lost, although with the possibility of different contents.
Blizzard said it expects this to be the last wipe it will need to do in beta. Even after the game is released, beta testers will be able to keep their stuff. So just consider this a first test run, and after the purge, players can start building for real.
Source: Hearthstone site