pi costs add up. zero would be lower of course. but when i got my pi, i had to spend money on a sd card, hard disk, usb hub apart from a case and charger. if you just need to see temperature of the room, just buy a digital clock that has a temp sensor. ikea has a cheap one (much cheaper if you can get it directly from an ikea store).
pi only makes sense if you want to log the data for further processing. but it is also not very portable as it would be stuck at the same place unless you make a portable unit powered by a power bank somehow.
pi only makes sense if you want to log the data for further processing. but it is also not very portable as it would be stuck at the same place unless you make a portable unit powered by a power bank somehow.