I can't comment on the ballasts at HD but I got two industrial magnetic 250w ballasts and housed them in a electrical box and wired them myself, I fired them up last week with 250w XM 10k bulbs and they look great, the downside is the electrical box gets hot so I placed two small ceramic saucers under it to let air under the box, the more expensive prebuild ballast boxes come with a thick aluminum housing which helps with heat, other than that there is no difference other than you have to wire everything yourself, also keep in mind you can't use HD MH bulbs, you need a higher kelvin bulb such as a 10k XM brand bulb, If you're a DIY'er and have the time I'd say do it yourself, If I had a bunch o' money I'd probably go with 2 Icecap electrical ballasts