$200/mo dedicated server + $45/mo prepaid phones. It was a very popular free ringtone website comprised of about 5 PHP files. It sent ringtones to users via MMS using carrier email address or via SMS (link) using AT commands to prepaid flip phones plugged into an old laptop at my house working off a queue.
Awesome!
People have supported millions of users on SQLite backends.
You can scale anything, the hard part is finding stuff people will force you to scale.