I think semoweb gave you the answers you need, but I'll clarify what a basic VPS usually includes (and semoweb can chime in if their packages are different).
Typically a basic un-managed VPS includes your choice of operating systems, such as CentOS, Debian, Fedora or Ubuntu in both 32 or 64 bit. I prefer to go with CentOS 32bit on a VPS with less than 2GB of RAM (64 bit is not needed).
Most everything else is an add-on. To host a website on your VPS, in most cases you will want at least a standard "LAMP" stack ... Linux, Apache web server, MySql and PHP. The VPS comes with linux. You have to add Apache, MySql and PHP. All of these are open source and free. You can install and configure them from the command line, logged in as root. Or you can have a control panel handle some of the details for you.
At semoweb, it looks like Kloxo is free, DirectAdmin is $9 extra per month, and cPanel is $15 extra per month. You'll have to verify with them, but in most cases, installing a control panel also installs Apache, MySql and PHP.
You save money by doing it yourself. A managed VPS that costs $40 might have the same specs as the $8.95 VPS at a basic VPS provider, but the managed VPS already includes a LAMP stack, pre-configured and ready to go. The managed host may also include cPanel in that price, as well as nightly backups that would cost you $10 a month bought a la carte, and monitoring service so you know when your site is down (another $5 for monitoring in 5 minute increments, although you can find monitoring for free in 30 minute increments.)
So if you need those extras, and are going to buy them anyway, you do the cost comparison this way:
But if you don't need a cPanel and can use the free panel Kloxo (or the command line), and plan to keep a backup of your site on your home PC, and will be OK with one of the free monitoring services that checks your server every 30 minutes instead of every 5 ... then you can save $30 a month.
I haven't used semoweb so I can't recommend them from personal experience (forum rules prohibit recommendations except from actual customers), but as you said you saw quite a few good reviews about them. I do know that the HostDime DC in Orlando is very good; I had a shared hosting account that was housed in that DC and the speeds for my EU customers was good.