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.