(110) 210 gram 10ah 10C lipoly's weighs 51 lbs (minus the box, solder and wire).
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3297
You could build a 22s5p ~88 volt 50ah 4,000 watt-hour 10C pack for $4,395. That way too, Lowell, you'd have an excuse to increase your controller to 500 amps