It doesn't have much worth right now. You should also buy YouCub.com if available. Since if you did try to sell it, you'd want to have both ways people could type in the domain if they heard it.
I agree with possibly $10 just above reg fee. It starts with a 'U' followed by an actual word. I feel that it would only have some real worth if it was developed.
u is often used to represent the greek letter Mu mean Micro
so Promoted as
uCUB or MicroCub then could be a great brandable name
Value $xx mid to $xxx low