I'm trying to realize a project with an Arduino powered weather measuring device. What I want to do is send a little box containing an Arduino and sensors to people I don't even know. They are supposed to install the box on their window sill, and I want it to somehow send the data - preferably wirelessly - to a webserver of my own. Of course the box should be as inexpensive as possible (as I want to be able to build a lot of these boxes), so buying a standard Arduino Wi-Fi shield seems out of the question. I looked around a lot for other means of getting the data online and after some time got into some pretty experimental territory. I'd like to hear from you guys if you think my ideas are feasable, which is the best one and if you have other ideas that are inexpensive and could work reliably. Different ideas as follows:
Using NRF24L01 or another cheap wireless device to relay the data from the box to another box which is equipped with an ethernet port and directly connected to a router. This has the disadvantage of needing another box and two different standards of communication and the advantage of having relatively reliable means of wireless communication. Also it's cheap: NRF24L01-modules cost 2 Euros max per piece and ethernet modules from china are even cheaper.
Using a Raspberry Pi and a standard USB Wifi dongle. The problem is, I have never owned or programmed a Raspberry Pi. Then again, I have some rudimentary experience in using OpenFrameworks, and I guess I could get this to work. This would probably take me a bit longer due to my lack of knowledge about the Pi. While this is not the cheapest of solutions, it probably is pretty reliable.
And the most crazy idea: Using an Eye-Fi SD card. I'm hoping it's somehow possible to code data into jpegs directly on the Arduino, save the images to the Eye-Fi and let the automatic upload magic of the Eye-Fi card do the rest. Later I could extract the data from the jpegs via Processing. Eye-Fi cards cost around 30 Euros for 4GB cards, so they may be an option - if I got all this stuff about "Relayed Transfer" correctly and the Eye-Fi cards actually are able to connect directly to a router and upload pics to some webservice. I'm not sure though that the Eye-Fis are able to penetrate much more than a window, let alone walls, which would suck. Also, I would want to grab the data automatically which may not be possible when the server it gets uploaded to isn't easily accessible via Processing.
Thanks for any insightful replies, Marius