If you dont have alot of cash & you want max lumens go with a 1,000 watt hps system with a magnetic ballast,digital ballasts have nowhere near the lifespan of a magnetic ballast,digital ballasts are not the big energy savers they're made out to be either,by the time you add up the energy savings plus the short life span of digital ballasts magnetic ballasts are the better choice.
Check ebay daily & be sure to use the "Distance nearest first" search feature,they come up very often & saving on shipping brings the costs down drastically,i picked up a 1,000 a few months back from ebay for right around $120.00 for a complete system.
BTW that ballast is an excellent ballast,i own several of them.