These lids look great, but i always like to save a few quid/bucks so i looked for the hygrometer units used in these lids online.
The hygrometer/Thermometer units in these jar lids are £1.00 GBP (approx $1.65 USD) each plus postage and packing.
I ordered 5 and with postage and packing the total came to £13 GBP ($21.43 USD approx) downside it will take a couple of week to arrive, but I got plenty of time before my next crop is ready to go into jars.
With a little DIY (a power drill & hole saw attachment) plus some glue, I'll be good to go for a fraction of the price.
Link - http://www.ebay.co.uk/itm/Mini-LCD-..._Measurement_Equipment_ET&hash=item2c88149b24
I hope this is of interest to anyone who likes a little DIY.
I'm very into DIY but this one's so cheap I figure it wasn't worth the work lol! Still, its a godo DIY project.