EDIT: We've been discussing these values and have decided to bump up the power gained from the free options as well as making the curve a bit more linear. New values:

Location Buff Starter Cottage Lodge Tavern
Forest Health +50 +100 +150 +200
Mountains Mana +50 +100 +150 +200
Volcano Damage +0.5 +1.0 +1.5 +2.0
City Loot Re-roll - - - +2%