I used to buy my mozzarella at Costco, but had the same reaction that you shared. It just didn't have any flavor. So I went on a search and tried about 5 before I found what made my Caprese to die for. Close my eyes and I was back in Tuscany. Shipped directly from Italy to the distributor weekly. Not cheap, but worth every penny.
http://www.pastacheese.com/buffalomozzarella210oz.aspx
Also from pastene.com try their balsamic cream. Like a very good balsamic reduction with that great intense flavor.
The things we do when the garden comes on strong.