Looking for a good Power Cap

[Spihc]

Hi folks,

Looking for a good Power Capacitor to fit on my GM V12XC esc, what should I look for? Any suggestions? Do I benefit from buying one from a RC retailer at $12 or do I go to my local electronics shop and buy one for $3?

Doesnt almost know what I'm looking for actully.

Edit: dont know if its any use: but its not for competing, rather bashing and having fun on a track.