A trophy is in the eye of the beholder... If it has value to you and was a memorable hunt, there is no reason why you shouldn't mount something... Big or small.
I have a friend who has shot some slammers for our area, yet he has a spike and a couple of basket bucks mounted... because of the memory of the hunt.
I actually had a small 8 pointer mounted this year.. He was not very big, but it was one of the best hunts I have ever had...
It doesn't hurt that my brother in law is a taxidermist and is doing it for only cost of materials!