To keep costs minimal you could use something like this:
http://shop.moderndevice.com/products/rbbb-kit ($US 13).
Get the 3.3V version. Then grab a microSD card with an adapter. Solder wires to the adapter directly from the board (MOSI/MISO etc.).
For time-stamping get a DS1340 board or similar, like this:
http://shop.moderndevice.com/products/jeelabs-rtc-plug ($US 12)
You obviously need some sort of temperature sensor.
Then you could set it up to sleep most of the time, wake every 10 minutes or so using the watchdog timer, take a reading, log it, and go back to sleep.
You would push the microSD card into the adapter to use it, and then pull it out and put into (another) adapter to get the readings on your PC. Or just buy the board you mentioned.
Also the minimal perfboard you mentioned could be another approach.