Try to have free tea tasting in small tea shops. After the tasting, if you like the service and feel obligated to buy something, spend less than 100 yuan unless you are very sure you would love the tea. If you like the service and are told all the teas are expensive, then ask to buy small samples and limit the expense within 50 or 100 yuan. You can always go back to buy more if you like the tea.
You don't have to feel obligated to buy something even after the free tastings. Many tea shops wouldn't mind it. Having somebody sitting in the shop tasting the tea would be like a window advertising and would attract more visitors, says the owner of the tea shop my aunt frequents. On the other hand, if the shop owner is very pushy then you don't have to feel bad not buying anything anyway, right?
Some of my friends say they would spend some money in small tea shops mainly because they enjoy the free tea tasting and talking with the shop owners. So if you think the money you spend is worth the service (but not considering the tea you buy) then it would be ok. If you think the tea is worth it too, then you can go back to buy more after tasting the initial batch.