rookie with first time brushless conversion/hyper 7

[halfcab]

so, next question, where to get the batteries, cheaply, I know hobbycity zippy packs are the absolute cheapest but since I have a slash also and my 5yr old has a stock slash what is the opinion of the elite 4800 25-30c packs in 2s and 3s from cheapbatterypacks run in series? as much as it seems to be a fairly over the top setup it was all gotten cheaply here and there so I am on kind of a buget only into it for about $425-$450 so far