The cheapest .to registration I could find, starting from $72 a year (2 year minimum).
NameRoute are a UK based domain registration company, sister to HostRoute, their hosting half. They're the cheapest registrar I could find for .ac and .io domains, $50 each.
Register .al domains for $140 for 2 years including trustee services. Best deal around as far as I can see, the net cost is $100.
Wild West Domains is the reseller arm of GoDaddy. Same company (I think) but WWD allows you to setup a whitelabel domain reseller system.
Dotster offer white label domain name registration and hosting services. The interface is fairly slick. Could be useful.