As an avid board game collector, I predict that they will sell out within a few hours. RIOT just broke through another dimension (the board game dimension) and people are taking notice of this upcoming game. Millions play League of Legends, and out of those millions, a couple thousand will easily purchase Mechs vs. Minions.
Aside from the PC gamers, board gamers in the US and other countries, such as Europe, greedily await the release of such an incredibly, well produced, and greatly affordable board game hoping to snatch a copy before a reprint, or before After Market Sales (which will, in due time, cause the price to inflate).
The QUALITY of this game is self-evident. The love of the creators transpires within the rule book and each, individual plastic mold.
Now, if only RIOT would allow other vendors to buy, such as Coolstuffinc, Miniature Market, or even Amazon, the news of this great game would spread like wildfire and their "street cred" would make many more buyers jump in on their next board game project. I'm already wishing for more, but this may be their one and only gem, and it will definitely outlive the PC game.