You can order one and have it transferred thru your local FFL dealer. Local dealers charge anywhere from $10 to $50, depending on location and market.
A C&R stands for Curio and Relic FFL license. It can be applied for fairly easily by almost anyone, it is signed off by your local LEO (usually sheriff), and once approved can be used to directly order various firearms that are designated by the C&R classification. Many old mil-surp firearms fall under this classification.
The disadvantage is that after your license, you have to record all firearm intakes and outgoings, modern or C&R into a journal that the ATF can demand to inspect.
If you don't mind having the gov't know about what you have in the safe, it's a great way to collect some interesting pieces. If you value your privacy more, it's not worth it and easier to pay the transfer fee.