I've had my dryer balls for a few years now. I bought this product when it had different packaging and for more money but it was the best investment I've had. Only good things to say. Can last for years, not forever but it naturally makes sense lol If you want something more affordable, consider the 'laundry tarts' which is the same but maybe they whiten or do something specific to theirs, not sure, but wool dryer sheets work.
Little advice, remember to use an essential oil scent of your choice. Also, when they 'stain' or start to collect hair and anything from your mixed clothing, it's easy to remove. Just take the time to peel off a thin tiny layer with your fingers. No scissors, they just feel like threads. So until they tear up and fall apart naturally from years of usage and age and decrease in size, keep them. Use separate balls for different clothing if necessary. Like one for babies/kids/sensitivities and one for dirty work clothes like in construction/labour etc.