Reddit mentions of Yamamotoyama Loose Genmai Cha Green Tea with Roasted Rice, 7.0-Ounce Bags (Pack of 6)

Loose leaf enthusiast here. Teavanna definitely has high quality leaves but you should check your options before you commit. Also - Teavanna(at least the one at South Coast) tries to push the sweet/mixed stuff too much - it's like showing off a steak with A1 sauce instead of letting customers try the delicious steak itself.

I highly recommend just buying tea in bulk on Amazon. If you're looknig for green, these are good : Link $14 for a 16oz bag will last you a very long time. Davidson's Gunpowder is cheap but robust and still delicious for its price.

If you want something with a more distinct flavor then go with Genmaicha. It goes great with food and is great to share with people because of its unique attributes: Link

If you're really keen on going to a store, a lot of the 'alternative' markets have loose leaf. Whole Foods has a pretty good selectoin of loose leaf - keep an eye out for the Rishi brand(Link), quality stuff. Make sure they sell it in loose form and not in the bagged/satchel form.

You can also use Yelp to find a local coffee/tea shop that offers loose leaf tea - they sometimes sell the leaves by itself. Link

Some shops I've personally been to that offers loose leaf tea : Zinc Café, Milk + Honey, Sweet Elle Cafe, Gypsy Den, & Kean Coffee.

Edit - I also recommend using Adagio Tea to buy tea. Great reviews and selection of tea. I have not bought from Tea Trekker but I did buy a book from them - great knowledge and selection of traditional tea from all around the world.