You should check with a tax professional, but per mine:
You should keep the receipts to document your purchases and the prices of the purchases.
IF you itemize (and for the majority of people it is not worth it to itemize, but it could be for you), you can deduct EITHER the price you paid for the donated item OR the fair market value, whichever is LOWER. So for the meter, you would use the price you paid, which was 0. For some enjoyable late night reading, you can Google and find this info in the tax code.
