Etsy seller LIMOchi makes these killer "poly leather" TARDIS purses to order for all your time-travelling bits and bobs. The seller claims that they are, indeed, bigger on the inside than they are on the outside.
( Not an official Doctor Who product , made by fan, to fan )... Measures: 28 x 16 x16 cm In blue poly leather and rigid cardboard. Also some details can be custom made. Sent in a beautiful box DW themed.