It depends on the species. The Village goes through a competitive bid process each year so the prices fluctuate based on nursery stock/climate conditions, etc. The available replacement tree stock is often in short supply. Lake Zurich is not the only municipality looking to replace trees.
The trees are roughly $250 - $400 per tree. So, the annual $50,000 budget gets the Village roughly 150 to 200 trees each year. Obviously, if additional resources become available in the future, the Village may be able to increase the number of trees planted each year.