Air conditioning cold on one side/warm on the other. on 2004 Toyota Avalon

When running my air conditioning, the air comes out cold on the 2 passenger side vents but warm on the driver side vents. Had a local mechanic check it and he said it might have a small leak in the evaporator core. He told me the cost to replace this would be $1,500. Yikes. I told him to just "recharge up the freon" or whatever the stuff is in there and hopefully this will work for now. Is this how much it should cost to replace such an item? Ouch.

Asked by for the 2004 Toyota Avalon