YOu get what you pay for.... Spend $80, and it will last for a while....
As for measuring PPM's/EC.... Buy yourself a Bluelab Truncheon... Its the best ppm/ec meter out there... Like $130... but believe me, you will be glad you did... Buy a cheap one, and those ppms will be off... and your plants will suffer... PH and PPM/EC are VERY important, and people who disregard them will pay the ultimate price...