A Bird In The Hand Is Worth Two In The Bush:
Having something that is certain is much better than taking a risk for more, because chances are you might lose everything.
A Blessing In Disguise:
Something good that isn't recognized at first.
A Chip On Your Shoulder:
Being upset for something that happened in the past.
A Dime A Dozen:
Anything that is common and easy to get.
A Doubting Thomas:
A skeptic who needs physical or personal evidence in order to believe something.
A Drop in the Bucket:
A very small part of something big or whole.