It looks like EPFL laboratories are prototyping an innovative ion engine which they claim can reach the moon using a tenth of a litre of fuel. The aptly named Micro Thrust engine weighs in at around a few hundred grams and is tailored to payloads that weigh 1-100kg. Though not suitable for manned flight this just may usher in an era of economical space exploration.
No word yet as to how much this power system costs. It would be nice to see the private and educational sector contribute to space exploration.