Cheapest persona fertility monitors???

[nobodysfool]

Does anybody know where the cheapest persona fertility monitors are sold?
TIA.

I used it for birth control actually.... very successfully for about 4 years... and then suddenly ds arrived, rather unexpectedly I might add (so they are just not foolproof!). Given that I was always aware when I was ovulating anyway, even though the machine tells you, I thought it was pretty accurate. Just don't know what happened during the ds conception month, as the machine claimed I wasn't even ovulating that month.... .