My recommendation is a pair of $15 boards with Mega32P, wireless radio/mass storage/Clock chip boards combined with the Networking software (free) RadioHead.
Sorry, but Sparkfun doesn’t sell these. Google for Anarduino comany’s Miniwireless board (board, not bare radio), and RadioHead software. I’d link to them but it seems bad form to do that on this forum.
I use these boards with the RFM22 and RFM69 radio options, with one connected to a PC with a large body of software I’ve written on top of RadioHead.
For low volume data, WiFi is too expensive, too power hungry, and the radios as above, being sub-GHz, have much better range and lower channel width which enables longer range and use of weaker signals. WiFI channel widths are 20MHz. These sub-GHz radios are well under 0.1MHz (100KHz). That’s the essence lowering cost/power/size and increasing range. And the radios are up to 100mW. The PC end is a serial interface - USB/Serial adapter - good one from Anarduino too.