Besides being able to have guns older than 50yrs old sent directly to you (or purchased in any shop regardless of your residency state), you can also get discounts at some retailers. Midway used to, but now it's only Brownells and a couple others. Discounts range from "are you kidding?" to pretty significant. When I first got my C&R, it only took 1-2 orders from Midway or Brownells to recoup my $30 fee.
There are also certain younger guns that qualify for C&R. They tend to be special commemorative guns, replicas of primitive firearms, etc. Those are specifically listed by the ATF, so don't assume they're C&R unless on that list.
Chris