According to Dave Meltzer, the recent UFC 174 pay-per-view, which featured a main event of Demetrious Johnson vs. Ali Bagautinov for the UFC Flyweight Championship, drew somewhere in the neighborhood of 95,000 to 115,000 buys.
A different article, one released by Yahoo! Sports, claims that the Johnson-Bagautinov fight drew 125,000 buys on pay-per-view.
Either way, the UFC 174 show drew the lowest number of buys on pay-per-view dating back to the UFC 163 show, which featured Jose Aldo vs. Chan Sung Jung for the UFC Featherweight Championship. That show reportedly drew 180,000 buys on pay-per-view.