If that is a retail price from a consumer website I bet you could get them for ~$9 if you order 10 or more direct from the manufacture.
If this was my project I’d make a blog, create an action plan, explain goals and impacts, and most importantly (but worthless without the rest) list partners with support / engagement levels (bronze, silver, gold, platinum). Essentially advertise the software, hardware, and people that are part of what you are doing. Bonus points if you create a YouTube channel and post in introductory video and project updates.
Then write up a very brief introduction and request for what the project needs and explain that any discounts, or out right donations will be well documented throughout the project life cycle and media channels you utilize (blog, YouTube, Twitter, Instagram, Instructables).
Any sales / marketing staff with a clue about this stuff should jump on it. It would be great exposure for there products, and be real life examples of DIY projects that are possible.
If anyone is looking for a project blog I may be able to help.
From what I can understand of your requirements, Meshtastic could be a part of the solution. As a platform it would support most of what you want to do. The base architecture is a mesh network for person-person messaging, with a recent move towards “plug-ins” or small applications that run on the device and can do things like relay sensor readings to a central server. The software is fairly configurable/tunable for different applications.
In your case:
GPS may be less important - Meshtastic expects nodes to be mobile. You may find cheaper device without GPS.
Meshtastic is also focused on low power consumption, battery powered devices, lasting up to a week. Not a problem for your case, but may have features you don’t need.
You’ll need some technical help - this is not yet a mature platform, so does need some knowledge to get started. That said, this is a helpful community.
Making electronic devices & sensors work outdoors, reliably, for years is always a challenge. These devices don’t have standard waterproof cases, power supplies etc, and that’s not well covered by this (software) project. Again, some community help.
Costs of <$10. Costs are always falling, as devices become more integrated, and this project is well placed to adopt new devices on the market.
You are probably also aware that there are devices called data-loggers, that typically run off battery and store data for up to a year, say, then need to be collected/downloaded manually. I used to work in that area many years ago, so not sure of current state of cheap devices, but it may be a better fit to your use-case.
Those are great ideas and I really appreciate that you share my enthusiasm.
I really need to understand the Meshtastic system before I go further so that I know how to make an intelligent response. It would be easier if I didn’t also have a very full-on daytime job. But there will be time - and better to build something effective and steady than trying too much too soon.
I’ll definitely want to come back to you about the project blog. That would be a fantastic resource.
GPS - definitely less important, though I guess there may be some environmental sensing applications where the precise GPS timestamp could be helpful. But the cost and power requirements of GPS are a burden we’d normally want to do without.
Low power consumption will be a must. We will need sensor nodes which can log daily or hourly for a year or more - so it’s a matter of the right battery, power-management and local power generation. I’m presuming solar PV in most cases. Robustness is an issue as well. The first test systems I set up in Malaysia were taken apart by monkeys and wild pigs! I learned a lot about what we need but I have a lot to learn about realistic, tough, autonomous, cheap solutions (which will work in hot environments where the solar UV destroys most cheap plastic enclosures).
I’m really impressed by the help being offered by this community - and, as you say, I’ll need help.
I’m aware of data-loggers as a technology but not the latest versions. I’m actually building a super-simple Arduino-based logger for a geophysical instrument (for a community project in North Macedonia) at the moment. The issue for this project is that the environmental variables we need to log for water management have to be updated hourly or (at least) daily if they are to be of use. So we need to send data to a server in something like real time. The amounts of data are small and the transfer time isn’t critical but it does have to be being sent, not being stored (though local storage backup’s a good idea too).
The more I describe this the more it sounds like what NASA are currently doing on Mars.
Hey - I have a friend at JPL! Maybe I should copy him in too …?
Also - for nodes which are in a “static” location, I believe Meshtastic supports setting a lat/long in the device settings.
Relatively accurate system time could come from the mesh (I think?), and nodes in a hand-placed location could potentially have the static location property set at the time the node is placed maybe with the app using the phone’s GPS (not sure if that capability exists in the phone app yet)
very interesting. the traditional LoRa model has sensors interfacing with a gateway to collect and publish the data, so you probably don’t want to change anything on the sensor side (and also keep it as cheap as possible).
evaluate if Meshtastic is really a requirement, it will add a ton of complexity. from a practical standpoint, its better to follow paths already paved. I would search for soil moisture sensors & gateway combo that can already work with MQTT, instead of developing one.