I'm so far removed from the hardware world. It's been quite a while. Being as you seem like you know what you're doing, I have a question for you.

What type of hardware could I run to host a web application, and it run smoothly? I don't especially think of it as being computationally expensive, but I want to plan in the event that I have moderate success. That said, I'd like to do this as cheaply as possibly. (I know, I know. This is a tall order.)