I figure it is about 2.25 liters and $200 worth of silver nitrate. I've been fortunate so far since I have received a bunch of silver nitrate as a gift and found an old pound bottle of it in an antique shop for $5. And, I have smaller tanks of the same design for doing smaller plates. The capacity of a 1/4-plate tank is probably 20% of the big one.
The collodion and ether are both about $50/500ml so that is fairly pricey too.
Some of the glass I use is $15/square foot. Ouch.
But it is all worth it. Wetplate is so much fun and looks like nothing else.