[techiferous]

Start with Heroku. It's actually quite cheap for low traffic.

At the same time, buy a $20/month Linode. Start playing around with it by setting up toy web sites and web apps. If you don't have experience setting up a server, then it's important to be experimenting with one for a long time because it takes a while to learn things. For example, you not only have to install and configure all of the necessary software, you have to think about security and resource utilization (memory, CPU, disk). You also are going to want to set up some server monitoring software such as serverdensity.com. And you're going to want to get used to managing web traffic (reading Apache logs, tuning Apache for performance, etc.). All of this takes time. But if you do this then if the time comes for you to switch away from Heroku, you will have experience setting up and managing your own web server.