Hi @Kelvin12I took your advice here and bought the Hanna TDS meter you recommended.
Hanna products are good. I have four of their devices. In the UK, their prices are high compared with the USA. I don't know about Australian pricing.
It is totally false economy to buy cheap meters. This is one of those situations when you get what you pay for. In terms of technical complexity (the device innards), TDS & EC meters are simple bits of kit. This is followed by thermometers and then, pH meters. Almost at the top of the ladder are ORP/Redox meters. And, finally for we hobbyists, there are what are known as photometers - this would correspond with Hanna's Checker range.
JPC