Quick search indicates mixed results on these and some switches being picky about compatibility, but if they'll work for you, I think it's hard to beat the price.
2M Cisco QSFP-4SFP10G-CU2M Compatible QSFP+ to 4SFP+ Breakout Cable - Monoprice.com
2M Cisco QSFP-4SFP10G-CU2M Compatible QSFP+ to 4SFP+ Breakout Cable - Monoprice.com