what AnnArborBuck said.
when one of my 400w electronic ballasts went out on my i happened on 400w ballast at HD for $29! this was obviously a tar ballast, but since it is in my crawlspace i did not care how warm it would get. this was a streetlight that was designed to be mounted on the side of a building. it included a cast metal case, lense, bulb, and ballasts. i only used the case and the ballast.
as long as you stick with american bulbs you will be fine. i have used iwasaki's (these fire on both types of ballasts, Coralvue's, and my favorite XM 10K's with this ballast. have not had any problems.
G~