If you would like to orient yourself to the ever-shrinking world of small satellite missions, here is an excellent class project by Alex Akins on the design of a femtosatellite mission. From the report:
While every satellite mission begins with a different idea, all of them share a common con- straint: cost. As the mass of the satellite increases with more instruments and larger struc- tures, the cost of ferrying the mission from Earth to Low Earth Orbit (LEO) increases. Cost also increases with semimajor axis of the operating orbit. While private companies such as SpaceX strive to reduce launch expenses, the fact remains that it costs multiple thousands of dollars per kilogram to insert satellites into orbit. For certain mission profiles, small, lighter satellites may be an appealing option.
Download and view the report here.