That's not how it works -- individual PBS stations don't make DVDs of the programs they air, unless they own the programs themselves. (To do otherwise would be highly illegal.)
Any item being offered as a premium for a pledge obviously *is* available to the public. If you're asking if/when it will be sold commercially, generally such packages are made available in retail outlets a few months after the initial PBS offering, so as not to discourage people from contributing to PBS. You can get it for a $90 pledge, and any PBS station across the country will happily accept your pledge -- don't be stingy! I was at the concert and can tell you it is worth it!
