The three-way catalytic converter on Taobao is much cheaper than that in the garage. Is it reliable?

It can't be worse than the garage. Garage needs site fees, labor costs, utilities, national taxes, local taxes and so on. They won't supply all the accessories of the factory unless they buy in large quantities or in large quantities every month. Even if the factory can supply it, the price is more likely to be higher than the online sales price. Online sales generally have auto parts stores, the sales volume is larger than that of a single repair shop, and it is normal for the price to be lower.