HostGator is an excellent host for your SilverStripe site. They are based in the USA, and offer a plan for as low as $4.95, which includes more bandwidth, disk space, and features than you'll ever use. The cPanel control panel makes it easy to administer your website and setup/manage email addresses.
This host also overs 24/7 support, which is a huge lifesaver when something goes wrong in the middle of the night.
I had a basic SilverStripe install up and running in 15 minutes (including the time it took to FTP the files, and create a database and mySQL user).
I've hosted with HostGator for 4 years, and over 30 of my clients websites, and don't have a single bad thing to say about them.
HostGator is ok I think. I use Ace-Host.net, even cheaper than the gator but I see that your post is actually an affiliate link so perhaps this is more like an advertisement. My hosting company also pays commission but usely affiliate links aren't allowed in forums.
affiliate link == spam :D