Using the M&M 3e headquarters rules, I offer the following TARDIS…
Size: Interior: Huge (Like, say, a castle). Exterior: Miniscule (Blue police box). 3 points
Toughness: 20 (Base value 6). 7 equipment points.
Features: Time Travel, Space Travel, Teleportation, Dimensional Travel, (2 points each to affect both the TARDIS and its occupants). Dual Size, Communications, Computer, Library, Secret (it looks like a strange blue box), fire prevention system, gym (complete with swimming pool!), laboratory, living space, power system, self-repairing, security system (locks and alarms. Good luck getting in the door without a key). 20 equipment points.
Total cost: 30 equipment points, 6 power points. Surprisingly cheap!