i have a 120 and was running the 250 hqi (de) and switched over to moguls (se) and like them a lot better. moguls are alot easier to deal with (removing and replacing the hqi's can be a pain in the butt and you dont have to deal with the glass shield either). i also think i get better "halide shimmer" from the moguls and better light coverage.
since you are planning for such a nice size tank. personally this is one area you dont want to skimp to save money. if i had just spent the extra money for the better stuff in the beginning i would have save my self some headaches and some money.
i would say bite the bullet get nice reflectors, ballast and go with the moguls, that would be my advice.
personally i use pfo ballasts (although they are out of business i believe however you can still get their ballasts from some online retailers and prob for a good price) and really like them. my lfs uses galaxy ballast with se radiums and i love the look of their lighting.
im using the lumen max elite reflectors se and really like them. ive got really good tank coverage with them. but i know a lot of people who use the homemade reflectors and there is a template to make them floating around.
so yeah there are a lot of options. i dont personally have any experience with hello lights but maybe someone that does can chime in.
if you need anything else you can feel free to pm me.....