There are plenty of things that _are_ within the reach of garage scientists, and exoplanet detection is one of them [1] as well as lots of other astronomy, as well as Biology [2] a surprising amount of advanced materials / electronics / etc [3] and more.
1. http://astronomyonline.org/Exoplanets/AmateurDetection.asp 2. http://diybio.org/ 3. https://www.youtube.com/user/bkraz333