1 Pair of silver wires will last anywhere from 1 to 2 years making 8 oz a day. Replacement wires are about 15 dollars american.
The other thing about making your own is you won't have any additives in your solution...bonus.
Use the boiling distilled water method for best results and store finished solution in a glass jar away from the light. I know people that have stoed it for over two tears and it still stayed in its colloisal state, ready to use. Do not use plastic to store it.
Also use a glass pot to make it. I use visions cookware and it works great.