Where to get TDS meter?

I've looked at places like Home Depot, Menards (if your in the upper midwest), Lowes etc and haven't found one so I eventually ordered online.. But after I got mine a place that I haven't looked would be any place selling the large bottled water or a hydroponics place..
 
yeah I check the local hardware stores with no luck.. ok.. i'll order online.. I am just inpatient and its a huge PIA to receive packages at my apt. Thanks :)
 
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