I do understand how you feel about not wanting to give up on it due to the cost. But in the end, the cost of getting rid of it is well worth it.
I had the copper IUD for years with no hormonal problems (I did have some cramping in the first few months). Overall, I really loved my copper IUD. It was the best birth control I ever used. I would recommend it again.
If you read all of the posts on this board, I think you will see that the Mirena adventure doesn't get better for most.