Can there be sorcery aimed at spending money on illness, given that it is said that sorcery affects the weakest part of the body and gradually causes illness, and is this consistent with the fact that Allah alone is capable of making us ill?

Magic can cause harm and illness, by Allah's will. However, a sorcerer cannot overpower the bewitched if they seek refuge in Allah and use legal ruqyah. One should not exaggerate in attributing every misfortune to magic. If there is a strong suspicion of its presence, it should be treated with legal ruqyah.