were to find ballast?

I have been hunting for a ballast for a compact fluorescent high bay light . it is the type you would hang in commercial building. it take a 70 watt 4 pin cfl . ballast read:

Fluorescent lamp electronic ballast
input120 vac 50/60hz 1.0a
class p
type 1 outdoor
use with 70w or 57w cfm lamp

i have looked around the net, but didnt find anything . maybe cause i just dont get all the electronic stuff. Thought maybe somone could help. Light is only 2 month old . a leak in the roof allowed water to drip right into the top of ballast. Well you know what happen then. Here what it looks like

70 Watt Fluorescent 15 In. Aluminum High Bay - L-1784 at The Home Depot