This sounds like what my DD2 has been experiencing. I think we were quoted about $3000, not sure if this was for the top only.
She was given two options but was told that braces will fix the problem whereas the retainer will need to be worn for a few years and a tooth would need to be removed. I think he was suggesting that the braces would need to be worn for 12 month then the treatment would be finished.
I hadn't thought about clear top and metal bottom. She suggested that the top ones be fitted on the inside rather than the outside but that is alot more expensive