OK, Shed, I did some legwork for ya.
I always use octopart when I'm looking for price and selection of these things. If you pick up the model number from a different source, you can just plug it into the search bar with octopart and you'll get a list of suppliers and prices.
So anyway, Digikey has both the single and double row strips in 22" length:
SI-B8U261560WW Samsung Semiconductor, Inc. | Optoelectronics | DigiKey
SI-B8U521560WW Samsung Semiconductor, Inc. | Optoelectronics | DigiKey
If it were me, I'd use single row strips. They'll run cooler and you'll be able to better spread them across the sky. There isn't much price difference.
I always use octopart when I'm looking for price and selection of these things. If you pick up the model number from a different source, you can just plug it into the search bar with octopart and you'll get a list of suppliers and prices.
So anyway, Digikey has both the single and double row strips in 22" length:
SI-B8U261560WW Samsung Semiconductor, Inc. | Optoelectronics | DigiKey
SI-B8U521560WW Samsung Semiconductor, Inc. | Optoelectronics | DigiKey
If it were me, I'd use single row strips. They'll run cooler and you'll be able to better spread them across the sky. There isn't much price difference.