I think there're two main templates for white of this ability that make sense to me:
1) If an opponent has a land etb and they have more lands than you, automatically get a treasure token.
This would be 2WW or 1WW if pushed.
2) If an opponent has a land ETB, they pay X or you get a treasure.
1W for pay 1, 1WW for pay 2? Add 1 if you want non-pushed version.
The 1W version of pay 1 for an etb *sounds* powerful but it's not really much more powerful than making lands enter tapped which is a 1W effect/1G effect. ((The symmetrical version for lands and artifacts is G -
Root Maze so stands to reason asymmetrical would be 1G)
I don't think this template works for white if it is actually
Rhystic Study where it's pay X on landfall or draw a card, since White is about equalizing resources not about turning other resources into cards. Although they do have
Smothering Tithe that turns draws into mana, I guess, so it might be feasible.
If so, I think pay 1 on a landfall or you draw one is a 1WW effect, and pay 2 is 2WW. Note, of course, than Smothering tithe should have cost 2WW not 3W - why they made that card splashable I will never understand.
You could template it as "other than the first land they play each turn" to reduce the cost significantly; I could see 'they pay one or you draw a card if a land other than their first land play would enter' as costing as low as W, since it's pretty niche.
I *could* see a whistic study that templates like:
"If an opponent draws other than the first in their draw step, you draw a card unless they pay X" which I would think is a relatively fairly costed as equivalent to
Rhystic Study -- 1WW for pay 1, 2WW for pay 2.
Of course, I think
Rhystic Study probably should have cost 1UU
![Smile :)](./images/smilies/1-smile-fb.png)