Yes, there are lots of bluetooth GPS that work. The one I hear about the most is the Bad Elf Bluetooth Receiver.
What I will be doing is a bit different. I've been able to get all my instruments repeating to my helm that is running OpenCPN. I think if I can find a NMEA deamon, I'm going to put the NMEA stream on the network as a TCP connection. Then use iNavx to tap into that stream on the iPad.
So far, all I've found is this https://github.com/thuss/marine-wireless-nmea-server
to make my helm a nmea daemon