Do they exist? Can anyone send me a link?
Not with T5 HO you cannot. At least with my 2x54W Hagen GLO T5 HO fixture. Take one bulb out, the other goes off.You could always omit a light from the socket to give you the outcome you are looking for.
I agree, the single-bulb ones do seem a bit pricey. Prices have been coming down for them though. I got my single-bulb 54W T5 HO GLO one at a inventory clearance from a place the was going out of business. New for only $60.I agree about the Glo light. I wouldn't waste my money.
I researched around on the internet on these and found too many people talking about the low quality balasts and workmanship of the fixtures and decided it was not worth it. You get what you pay for.Fishneedit as mentioned previously is a good fixture for the cost. You could maybe pick up one of those and adjust as needed