I want to get a Yellow or Orange lamp for my T5 8W preheat fixture I have recently Obtained, so I can use it as a night light.. looking online seems to show that they're as rare as unicorn horns.. Not sure if I'm looking in the right places or if they simply do not exist...

I think your right that they don't exist, I looked in both of my old GE catalogs and my sylvania catalogs and found only different colors of white HOWEVER, if you google T5 flourescent color sleeves the options are almost endless! so a sleeve may be your only alternative good luck!

Well that is unfortunate... But i guess the color sleeve idea would be better anyway, since if a yellow or orange bulb exists, they are rare, so I would have to find a replacement, whereas if I use a color sleeve, I can just replace ordinary T5 lamps..