So 150 or 50 gold?
When your potentially blasting a pair of medium pokemon each round, then yes i think 150 gold is a good starting point.
We should likely also keep in mind, that since pokemon lacks shields, then ranged attacks like these will be Super Effective.

Hmmm, that sounds better yes. Also swamps rarer than mountains. Will do.

I'm thinking of adding them at the cap too like the Onyx with 1/month rec limit.
I think it would balance with how the pretty powerful Onyx is found in a cave?
But being allowed to recruit 1/month is likely a good call.