besides the already mentioned OsCommerce / XtCommerce, you can try to use a "ready-to-use" solution. In all following are paypal and other payment options included. Please see the websites for details.
1) One I really enjoyed (but have not used so far) is Enstore:
If you have somebody around who is good with HTML/CSS you can give it a good look. If not, you might be check out several "hire a designer" websites.
2) There are some alternatives to enstore. A friend of mine has started a Cider shop (see it here as an example) in germany. He used the Strato Webshop. They start at 9,99 pounds (UK).
3) Very similar to Strato, but more huge is 1&1.com. They are offering a full hosted shop for up to 50 products for 11.49$. I have webspace there myself and another friend has space there too, we both are very happy with this provider.
4) If you are willing to learn HTML/CSS yourself and don't want to use the read-to-use-shops you can build your own (yes, with plain HTML). In that case the complex part of the shop is being hosted at Mals E-Commerce. You just need to add special kind of links to your HTML. Well, this might be cheapest as you need only a small webspace package (maybe 3$ a month?) and can do everything yourself.
You can decide with such kind of matrix:
- How good should it look? -> Enstore
- Should have all features and ready to use, but cheap? -> 1&1/Strato
- Should be cheap and I will do everything myself? -> Mals E-Commerce
- I have somebody who can install and maintain my stuff? -> OsCommerce
If you have a bit money, check out Enstore. It is the one I like most.
Good luck with your tea shop - and don't forget to send me an e-mail when its on, as I am addicted to green tea.