After plenty of clicking around after logging in I found this page: https://courses.edx.org/course_modes/choose/MITx/15.390.1x/3T2014/ https://courses.edx.org/

After plenty of clicking around after logging in I found this page: https://courses.edx.org/course_modes/choose/MITx/15.390.1x/3T2014/ https://courses.edx.org/course_modes/choose/MITx/15.390.1x/3... Which indicates the minimum fee is a $50 contribution. It feels like edX could do much better in making that pricing information available before enrolling but perhaps their testing has indicated otherwise.