What do you want to weigh???
If just for food, the ones you buy at Woolworths are fine, but if you want to weigh out a serve of DMMA at 0.025 of a gram I would suggest staying away from the Woolworths scales, as you will probably OD and be admitted to emergency at your local hospital.
So all things are relative, I have four sets of scales, the $20 kitchen ones to weigh servings of food and for general kitchen use.
Another set that weighs down to 0.1 of a gram, bought on eBay can be used to weigh protein powder, creatine, glutamine etc
Another that weights down to 0.001 one a gram, ie one thousands of a gram, where I can weigh out 25mg (0.025 gram) of DMMA or 50mg of caffeine powder also bought on eBay.
And finally another set that I use to weigh myself, accurate to within 100 gram or 0.1 of a kilo.
So one scale will not do everything you will need more than one depending on what you want to weigh.