The courier brokers i have personally used include the ones mentioned, but add
http://www.parcelsplease.co.uk/ or
http://www.collectmyparcel.com/ to the list. Worth checking them all since prices vary, one will not always be consistently cheaper than another.
I agree with cosmic though, generally i have found transglobal to be the cheapest both on imports and exports. They also have imo the more professional service.