The disclosure relates to the technical field of sintered type NdFeB permanent magnets, in particular to a low-cost rare earth magnet and manufacturing method. There is provided a method of preparing a high-coercivity sintered NdFeB magnet including cerium comprising the following steps: (S1) providing alloy flakes composed of RxT(1-x-y-z)ByMz; (S2) mixing the alloy flakes, a low melting point powder, and a lubricant, then subjecting the mixture to a hydrogen embrittlement process followed in this order by pulverizing the process product to an alloy powder by jet milling, magnetic field orientation molding of the allow powder to obtain a blank, sintering and aging treatment the blank; (S3) coating a film composed of a diffusion source of formula R1xR2yHzM1-x-y-z on the sintered NdFeB magnet; and (S4) performing a diffusion heat treatment, followed by aging the sintered NdFeB magnet to obtain the low-cost rare earth magnet.