I'll agree with bricktop that HTG offers a great warranty but the largest mistake I ever made was going with HTG for my initial purchase. Everything they sell is outrageously expensive for the quality. They sell 1kW nondimmable lumateks for $360, this place sells dimmable lumateks for $250...
http://www.urbansunshine.com/digital-ballasts
There own alibaba chinese ballasts are even more expensive than the competitors lumateks... Thats NUTS!!!
They guaranteed I wouldn't be able to find a hortilux cheaper than their bundle - week later found out that all 4 local hydro shops sell them for ~30% less...and offers a 1.5 year warranty on all their bulbs.
He he, even alibaba offers a factory 3year warranty -
http://www.alibaba.com/product-gs/368453901/Digital_Ballast.html?s=p