Villagers trade rebalance with emerald blocks

Right now, villagers are really OP, and don't really require a lot of work to be done in order to get really cool gear / enchants for a low price

I propose that instead of using emeralds to trade books / gear, it could be replaced by emerald blocks. The exchange could be equivalent to what is right now (a trade costing 9 emeralds would now cost 1 block) in order to maintain the current prices, but it also fixes the current system by not allowing the player to make the prices too low, by having it cost a minimum of 9 emeralds.
I think this simple change alone could fix a lot of trading's current problems, because right now, a lot of the trades are very cheap and fast to get, making the system as a whole worse.