I like the idea of a Garmin handheld hiking GPS. Or maybe an automotive dashboard unit. But I looked on Craigslist and Ebay, and even the used ones are as noted, around $200 if they are modern. I wish I had more uses to justify paying that much, but I'm too cheap to spend that for my very occasional use.
I also Googled to learn the present state of the art in phone precision GPS. I thought it was farther along but it looks to me like this is still at the experimenter stage. For example 3~5 meter accuracy can be obtained IF you customize a precision-time application so your Android GPS ap can sync its clock to a frequently-updated master time standard. And the author of this precision clock software is asking for volunteers to host time servers in local communities all over the world, for the locals to sync to. That's definitely pre-release software development.
I never found an off-the-shelf real time precision GPS/mapping/waypoints etc ap. I think in theory the phones are capable of it, they triangulate satellites same as a real GPS and can triangulate cell towers also for a faster lock - but as I said the software to make precision observations and get the readings into an on-screen map - in real time - seems to still be in the hands of experimenters.
Mike, I looked at the QGIS website. I think their emphasis is developing software to read, integrate, overlay etc existing GIS data. I didn't see a section about acquiring data in the field, but it must be in there somewhere. I searched the current-release documentation for the word 'Android' and got only one hit:
... runs on Linux, Unix, Mac OSX, Windows and Android and supports numerous vector, raster, and database formats and functionalities....
so after that search I don't know what else I could use from their site, if I don't buy a Garmin or similar that outputs industry-standard readings.
Maybe the big farm GPS systems for tractor steering etc are all closed proprietary systems - my searching on phone GPS aps didn't find any overlap at all.
I guess I should explain that this inquiry is as much intellectual curiosity as it is farming necessity. It's not that difficult to just drive every second orchard row looking for the new trees. I just thought an application would be out there by now.
Still searching ...