I want to send it from Minhang, Shanghai to Jiading, Shanghai, about15kg. What is the cheapest express delivery or logistics?

Calling a courier company is really expensive, and the cheap delivery method is to go to the post office. You can send a big bag like this to the post office. The post office can also send parcels by slow mail and express mail (ems express). If it's not urgent, you can deliver it slowly. Last time I sent a large snakeskin bag (I forgot the specific weight), and the weight was only 8 yuan. If you find a bag or box to hold things yourself, you don't have to pay for the packaging bag. Very cheap. It takes three days if it is fast, and a week if it is slow. (ps: the post office needs to check items, so don't seal them with tape in advance and then take them out for inspection)