They are non-free to manufacture, but most likely they have to pay patent license fees to the likes of RSA or something. Also the server hardware does cost a bit to maintain given the number of people (including phone versions) they have to support.
As for sharing a dongle between logins, no way. There's no way a company would let anyone else have access to the key sequence. That'd be the dumbest thing ever and basically make them useless from a real security perspective.
Given that SecurID tokens can cost upwards of $200, $6 is a steal.