Hi there, anyone uses batt pack for Metz 54MZ-4 flash? Care to share what brand/model/price/broughtfrom and how do you find it?

Have both canon 580 and Metz 54MZ-4, but tends to use metz more as i like the color turn-out better, so am looking into getting a batt pack for it...Thanks in advance for all advice! Cheers.