Where can I host my Plone site?
To make your site available for Internet, Plone requires a Plone friendly hosting provider of a virtual private server (VPS) minimum.
Plone is an application that runs its own daemon processes (background services). These usually require admin level access to the server to run, or at least Plone friendly hosting provider. Please see the minimum system requirements.
This isn't that big a deal for large Plone projects, who typically run on one or more dedicated servers, and have IT staff (or outsourced) with the appropriate skills. For small scale Plone hosting you might need to do some work to select a good hosting solution.
Check whether a hosting provider supports Plone
Ask them! Say "Hey, [friendly tech support person], does [your web hosting provider] support Plone? Here are the minimum system requirements."
If your web hosting provider does not explicitly mention that they support Plone, then they probably don't.
Plone hosting companies
Plone's popularity has led a number of web hosting companies to specialize in hosting Plone (and applications that have similar slightly-out-of-the-mainstream server requirements like Django, Turbogears and Ruby on Rails).
Typically, these companies offer a variety of service plans in the $30 and upwards/month range. More money gets you: more RAM (which supports a larger, more complex site), more bandwidth, more disk space, support options, backup solutions etc.
Hosting from your Plone consultant
Virtually every professional Plone consulting shop out there has dedicated servers on which they can host their clients' projects. So, if you're working with an established Plone consulting shop, you probably don't have to worry about setting up your own hosting. Ask you consultant what they can do for you.
Of course, if you're self-implementing Plone, then you may need to consider other options.
Virtual private servers
If you're more technically inclined, and would rather accept a greater amount of responsibility in exchange for greater control over the fine details of your hosting environment, you might want to consider a virtual private server (aka a "managed virtual server") for hosting your Plone site.
A virtual private server hosting arrangement uses "virtualization" software to split a single physical machine into several completely independent systems that share only processor cycles, disk space and RAM. A virtual private server environment thus fills a very important niche in between inexpensive shared server webhosting accounts (your typical $5-20/month special) and more expensive dedicated servers.
You can expect to spend $20-$100/month for a virtual private server environment that is suitable for hosting one or more small-to-medium Plone sites.
Virtual private servers are a fast-growing segment of the web hosting provider market, thanks in large part to the fast-growing popularity of non-LAMP environments such as Plone, Django, Turbogears, Ruby on Rails, Pylons and more.
Dedicated hosting is the same concept as the virtual private server, except instead of buying a part of a server, you are renting an entire machine in a remote location. Dedicated hosting is often price competitive with virtual private servers and in some cases might actually offer more memory/processor speed/transfer at the same price level.
Inexpensive, commodity dedicated hosting providers can provide machines for as little as $100 a month. More expensive and hands-on offerings can run into as much you want to pay.
You can run Plone on Amazon EC2 cloud.
Why not use my current $5/month hosting provider?
It's an old adage: "you get what you pay for." More accurately, though, you don't get what you don't pay for.
In the case of "el cheapo"1 web hosting providers, what you're not paying for is any kind of helpful support. That's labor, and labor is expensive. The entire business model of commodity hosting providers is to gamble that you won't have any tech support questions, and to provide the least amount of help possible if you do. This might be fine if all you're trying to do is host a few static web pages, or run a simple PHP script. But in the long run, ultra-low-cost commodity hosting providers are rarely a good value.
1 Which we define as $5-20/month hosting providers selling shared LAMP instances.