[ionrock]

I chose a VPS b/c I wanted to run Python web apps, which traditionally don't work with shared hosting environments. Most shared hosts have daemons that kill long running processes. If you have a python script running for a long time (even if it is running your site) it would be killed. This seems to be the biggest reason in my mind for running a VPS over a shared host.

In terms of cost, a VPS usually will cost more as memory usage is something you'll have manage. For example, I would have liked to run MongoDB on my VPS but just didn't have anywhere close to enough memory. Not a big deal, but if you're using it for a business then it is important to understand what you're getting into in terms of memory usage and what services will need to run. You have to allocate resources for not only the web server, but any databases, scripts, etc.