Software Cost

FOSS is usually available at zero cost.

Using readily available free software replacements for proprietary software (e.g., replacing Microsoft Office with Openoffice.org) can often save thousands with very little no effort.

Proprietary vendors are cracking down on use of unlicensed or copyright-infringing software in both the developed and developing world.

Disclaimer: non-profits should be careful not to confuse this with the total cost of ownership. Knowledge, maintenance, transitions plans and more which each have a price.