Did you mean different species, not the same strain grown in different conditions?
If it's different species you can't really compare, a cubensis is one kind of trip, pan cyans for instance is a way more intense trip for me at half a dose of that of cubensis.
As for growing conditions/different substrates it only affects yield not potency in my opinion.
I will only ever pay "expensive" for something that is really hard to grow or rare like liberty caps, cubensis varieties on the other hand should not be more than R50, R150 is a rip off.