I went with the Lumatek LK400 - there are a couple units used on eBay. They are 4way adjustable, including the HQI version (250w, 275w, 400w, 440w). Lumatek produced a great product (the LK400 model is no longer produced), I'm sure it is on par if not better quality than the LuxCore ballasts.
You can pick them up for around $40-60 used.
-Mark