My father is a florida resident that happens to have a house here in NJ.
He has no NJ id of any kind.
He only applied for the FID to cover his butt when bringing NJ legal firearms to this state.
No need to purchase anything here.
As the post above says "Anyone who is qualified can get an NJ FID card and use it to buy long guns in NJ regardless of what state they live in"
Just call the state police and ask for info.
I did all the leg work for my Dad and the State Police were actually very nice on the phone and at the station.
Funny note......when he went to the station to pick up the card an officer (not a detective) was clueless how he could get a FID not being from NJ.
My Dad is a Florida res...FL Drivers License, ect.
Has a home here in NJ like you.
He has a FID card with his Florida address on it.
He had to go to the state police to have the application done.
Three months later FID card in hand.