[MetroMPG]

In general terms, for a typical DC system conversion, you will have about $6,000 - $10,000 in parts, plus about $1,000 - $1,200 in batteries. If you go for sealed lead acid or exotic batteries, or super high performance racing components, the cost will go up. AC components will cost you $8,000 and up for the parts, and probably $2,000 or more for batteries, as these are higher voltage systems.

http://www.electroauto.com/info/cost.shtml