I have a Standard Horizon VHF that includes an AIS with nema output. I would like to send this nema signal via wifi to my tablet which is running navionix, There are devices that cost several hundred dollars. Can someone lead me to a cheaper device.
Look at the Yakker by YakBits. Made in Australia and is something like $69 plus shipping. It is tiny and it works great for your application. I had it for several years on our sailboat until I no longer needed it there. Now I am moving it to a small power boat in the exact application you are talking about.
It takes both NMEA 2000 and 0183 data and makes it available over a wifi gateway. You'd likely have to modify the code to get the specifiic NMEA sentences you're interested in forwarded to wifi