Tea is one of those things that seems more expensive than it is, a lot of times, I think. Because it's sold by weight, the prices look very intimidating, but tea leaves weigh very little so even a few ounces is a decent amount.
Prices totally vary based on a ton of factors - type of tea, where it's from, etc., etc. Same as coffee, wine, that kind of thing, you can buy tea that's a few dollars an ounce or tea that's tens of dollars an ounce.
I'd look for a small, independent tea shop in your area. Like wine shops, they'll usually give better service, they're more knowledgable, you can form relationships, etc.
Barring that, you can certainly look around online, you've got some good links in the thread. You might look around
the Adagio tea site - they're a tea brand, sell loose and bagged tea online and in markets. I like their stuff, but they also (the link is to their green tea page) have a good site I think. You can look at the quick shop links and see the differences in prices and then read descriptions and reviews to see what the differences are that drive the prices.
Also, not for nothing, but is he using the correct size tea ball? Sometimes, people not familiar, may pick up a pot-sized tea ball and not realize it's meant for whole pots not cups. So... you might throw in a cute tea ball/strainer. There are plenty, some shaped like two spoons clamped together.