Beta is an unsupported server where you cant buy vip or other perks.

I bought maria, have never used her in a battle outside a couple of test battles. But as for perks of spending cash, I much prefer gaining a new hero then being able to auto spin the tavern or something like that.

Provided the hero is just an option even required is debatable, but not overpowered. I don't see the problem, even with a limited time sale.