There are quite a few options mate. Some decent brands to look at include lumatek, maxibright, sunmaster and lummi. Thats on amazon uk probably some differnt brands in the states if thats where youre from. I would start of by deciding the wattage you need 400w, 600w or even 1000w. Depends on the size of the grow area and temperature you can handle. The older magnetic ballasts are cheaper than digital ones but less efficient. So decide on your wattage needs (and if you want a dimmable one) then search in your budget and see what options you have
Edit- there are probably dozens of other good brands those are just what came to mind.
There are some great threads in the lighting section at the minute about hps/mh