illuming.com sells nice 70watt halide retros FWIW. I used to have one on a 10g, but sold it. I will never use 70watt halides again... they just arent worth it. Cost wise, you can get a 150 or even 250watter for about the same (okay, the $10 regent reflector DIY is hard to beat), and the bulbs cost alot for their size.
The real reason I dont like them anymore though is bulb selection. The only bulb worth a spit of output is the Ushio 10,000K, and so that means you will most likely still want to use actinics to balance the light out. Beyond that, the bulbs are few and far between... maybe only a half dozen bulbs made in all. So if you dont like what you see... its hard to change. All of the 14,000K and 20,000Ks are too dismal, even for a 10g. Tunze makes a 15,000K, Aqualux (is that the right name? I used to have one but forgot) makes a 14,000K that is worthless. Aqualine makes a 20,000K that is dismal and $100 per bulb. With the 10,000K being too yellow, and the blue bulbs too dismal, you either end up adding supplimental actinics (for a butt-load more $$$ and operating cost), or upgrading to a 150wattDE so you can run a nice 20,000K. But the one thing to keep in mind is that with one halide bulb as your main source of light, your options for color are few. With several smaller lamps, you can mix and match colors to your liking.
FWIW, I think the best option for a 10g is to upgrade to a 24" long tank and use 2' T5 bulbs. A 2x24wattT5 unit with a GE 6500K and a ATI blue+ bulb will shred the output of a 70watt halide, for less watts. IF you want more light, or more blue, you can have 4x24wattT5s, and really have a bright tank.
$99 solution... with bulbs. individual reflectors and waterproof endcaps...
http://www.customaquatic.com/customaquatic/itemdetail.asp?itemid=LT-CV-T5RK2-2
^^^ you can start with 2, and if you want more, just add another. Also, the use of a small computer-style fan blowing across the bulbs would be a good idea. T5s arent really hot, but sensitve to heat. A fan can boost output by a good 20%, and extend the life of the bulbs so you can get a good 2 years from a set of bulbs. FWIW, the CoralVue T5s it comes with arent the best, but for $99... what do you expect? They should still last you a good year though and then you can swap them out for some nicer G-man/ATI/Aquascience bulbs. For frogspawn and zoas... this light should be plenty, giving you about as much output as a 2x65wattPC fixture (those reflectors are key!!!)
Also, as long as you dont mind a couple inches of fixture hanging off the ends of the tank, you can use these 2' T5s on a 10g still and not have light coming out the ends. The bulbs themselves are only 22.5" long, and the lighted area doesnt start until a bit over an inch from the ends, so they truly are only 20" long.
