With thousands of bottle caps of course
This guys sent in over 2000 bottle caps to Bethesda requesting a pre-order for Fallout 4, and turns out they are honoring it.
They already said they wouldn't accept this a second time, but I dont think that would be a wise move anyways. Shipping alone must be like 15 bucks. Not to mention the time and/or money to collect the bottlecaps