What's the best way to get a shopping cart on your website if you host it & know HTML?

I want to sell my products online. I know HTML and host my website at home. What is a good, inexpensive way to do this? I'd prefer something that is inexpensive, and that I might be able to upgrade in the future.. but definately inexpensive to start, since I want to see how it does first before putting a ton of money into it.

Paypal's shopping cart is free - you only pay fee when you sell something and that's just the normal paypal fee which they deduct from your acct automatically