Zoro's swords are also free upgrades
They are not, he earned every single one of them
Wado by becoming Kuina's rival and inheriting her will
Sandai by taking on the curse no one wanted to, because they got injured or killed
Yubashiri by the shopkeeper getting impressed with how Zoro dealt with Sandai
Shusui by defeating Ryuma in a 1v1 fight, despite being nerfed with only 2 swords
Enma by defeating Kamazou and saving Hiyori, who was the owner of the sword and decided to give that to Zoro while also trading for Shusui to stay in Wano
how did Sanji earn the body modifications? he was born by Judge, that's it