University courses provided online in form of MOOCs (Massive Open Online Courses) are gaining increased attention, yet their pricing structure is rarely studied. MOOCs can be treated as knowledge products, and MOOC platforms, therefore, become the marketplace for market-participants to trade those products. A functional knowledge market cannot be established without an appropriate and reliable pricing model, but so far, there have only been a very limited number of studies focusing on the pricing strategies in MOOCs. This study fills this gap by providing a systematic price analysis on one of the largest non-for-profit MOOC platforms, edx.org. In doing so, we establish a model to explain the price differences among different courses. This study can act as a well-grounded starting-point for future MOOC-pricing studies and knowledge products' valuation research.