Hardware for mower?

Looking at hardware for a guided mower. Conventional steering (not skid steer). I obviously need a big servo for steering and speed and my job is designing motor controls so I think I have that covered. My questions are about the gps and rc hardware as I have no experience with it. From what I have been able to figure out I need:

A base station. I have a local CORS station that I have been able to get an account for (free state run) and connect to via the internet.

GPS receiver. Looking at F9P receivers but am open to others. That seems to have a lot of support. Sparkfun module is about $250. I see NavSpark NS-HP-GN2 : PX1122R is considerably cheaper at $110 but wondering how they compare. They both need some custom wiring so that seems similar. No idea how performance compares.

GPS multiband antenna

Rover controller such as Pixhawk 4. A little lost on this one as prices seem to be all over the place and apparently multiple companies make things they call Pixhawk 4. Have seen radio link, M8N GPS and pixhawk 4 for about $130.

RC transmitter/receiver. Seems like this is almost a necessity and thinking I could use it for other rovers/drones/etc too.

Radio link to send gps corrections to rover. This could be wifi with something like raspberry pi on the rover or simple 2 way radio link.

Ext. compass. Some GPS or controllers include this but have read that external compass is useful improvement.

Looking to do this on a budget while not going for the cheapest junk out there that is reasonably straightforward to set up. Soldering and construction isn’t a problem for me. Software configuration and how all the parts electrically connect will be more of a learning curve for me. Sparkfun has some pretty good guides to hooking things up which is a big plus.

Looking for suggestions on hardware and info sources to read. Where should I be looking for info on similar projects others have done? I have found deep south robotics and several others but need to do some more reading.