I have two feather dusters in my 9 gallon tank. One is the brown and the other is a lime green color. I can't remember exactly how much they were each but, I think it was like nine dollars. They are both doing great. I've had them since March of this year.
If I can keep them alive in the nano, anyone can keep them alive.

these are the two that I have...

the first one is the hawaiian and the second one is the green/yellow.
this one is pretty... unfortunetly, I don't have it (yet)...
pics are from: http://bluezooaquatics.com/livestock/product_info.php?id=2016 (one of TRT sponsors) they tell you all about the care of them on this site - 'intermediate care'.