Step 1: Split the idea of software cost.
GIS software is either commercial (you pay for a licence) or open-source (free to use and free to change).
Step 2: Check MapInfo.
MapInfo is a paid, proprietary product, so it is commercial.
Step 3: Check ESRI.
ESRI makes ArcGIS, which needs a paid licence, so it is commercial.
Step 4: Check GIS Cloud.
GIS Cloud runs on paid subscriptions, so it is commercial too.
Step 5: Check Quantum GIS.
Quantum GIS (QGIS) is free and open-source, built and shared by a community at no cost.
Step 6: Conclusion.
The one that is not commercial is Quantum GIS.
\[ \boxed{\text{Quantum GIS}} \]