Go for the TARDIS option because you could make a lot of money with time travel anyway. Invest your money in saving accounts with high interest rates, travel forward in time by a hundred years or so, and withdraw lots of more money. Go back in time and buy shares in today's massive companies when they were in the embryonic stage. You could make so much cash by applying hindsight to the stockmarket- and that hindsight is readily available if you have the TARDIS.