There's a lot of 7 1-lamp preheat F40T12 ballasts, LPF Universals with the older dark blue label on ebay right now for a really low price. If I didn't already have about that many 1 lamp F40 preheat ballasts, I'd probably go for that. None the less,
here's the link. I think these are older ballasts too. I have one identical to those ones that you can see in my gallery. That ballast is currently inside of a F40T12 strip fixture.