Permanent that generates creatures is never UP. Its a damn permanent. There are only 2 perma control cards on the stick, one of which is not even that good.
A permanent that cost 30
and generated 0|1s would definitely be under powered. Likewise a permanent that cost 1
and generated 10|10s would definitely be overpowered. Somewhere in between is the balanced standard that should be aimed for.
Because there is less permanent control than creature control, skills are more valuable on permanents than on creatures. When I asked how much more valuable they are the consensus was the skills increase in value by 50% on average.
@ Drobbit
I would be disappointed if you change the cost based on my opinion alone. I definitely think waiting for more opinions is the responsible thing to do.