I dont work in NYC, but I am on long island. The only RNFA I know of worked as an RN in the OR, then became an NP/RNFA and worked with a surgeon that he knew from his time in the OR.
Im COMPLETELY guessing but id imagine unless you have major OR experience, rnfa experience, or great networking contacts that it could be relatively tough to get a specific "rnfa" job. Then again I think there might be hospitals who just hire you as an OR nurse and pay you slightly more knowing that you offer flexibility for them.
But its not like becoming an RNFA is a huge time/monetary commitment either that you need to worry about it panning out long term.