I used Qiagen before
Here is brief protocol
1. cells were permeabilized by resuspension in buffer containing 210 mmol/liter sucrose, 20 mmol/liter HEPES-KOH (pH 7.5), 10 mmol/liter KCl, 1.5 mmol/liter MgCl2, 1.0 mmol/liter EDTA, 1.0 mmol/liter EGTA, 1.0 mmol/liter dithiothreitol, 0.1 mmol/liter phenylmethylsulfonyl fluoride, 1:100 protease inhibitor mixture, and 0.04% digitonin.
2. Keep it for 45 min in ice (in between mix it) and followed homogenization using Dounce homogenization procedure it look like this (do five times up and down )
3. i also passed the solution using 21gugage syringe to further homogenize it.
4. Then sediment nuclei and cellular debris, cell suspensions were centrifuged at 600 × g for 10 min at 4 °C. The supernatant was centrifuged at 15,000 × g for 30 min at 4 °C.
5. After this centrification, the pellet was defined as the mitochondrial fraction.
I used this mitochondria for western blot to analysis protein trans-location experiment. but you can try it.