Should I give my fiancee an almost-new, but preowned ring?
That depends. What is your reason for doing that?
I want to buy my beloved a great ring, but I can't afford a new one
It's nice that you want to give your fiancee an glamorous ring as a symbol of your love, but it's understandable that financial circumstances outside of your control prevent it. As long as you are honest with her, I'm sure she will love any ring that you give her.
Thanks. You are right I have to be honest with her.
Yeah honesty is important in a relationship. It will help you both understand each other and know how you really feel so that there will be less problems later on.