It's not discounted. With Hagerty, you must carry the coverage limits with them as you have with daily drivers. You have to fax or mail them a copy of your current policy.
It's just cheaper because they understand that these cars aren't used as daily drivers or abused and are babied. The risk factor is much less.
1baddodge, I pay the whole thing up front. for $118, I'm not going to break that down into a monthly premium. I only pay once a year.