This paper analyses the influence of selected magnet materials on the design of slow-speed permanent magnet synchronous generators for use in wind applications. The design procedure, including setting of the initial design parameters of the machine, calculations of machine dimensions, magnetic flux in the air-gap, and electrical parameters as well as the selection criteria of permanent magnets for the use in the permanent magnet generator is presented. According to the calculations, a generator prototype is constructed with four different rotors, where different magnetic materials are used. The machine is tested using the different rotors and the influence of the different magnetic materials to the output characteristics of the machine is shown. The price to power analysis of the used magnetic materials is provided and conclusions for the possible machine design benefits and drawbacks are presented in the study. The investigations carried out show that NdFeB magnets are the preferred ones in terms of the performance and weight reduction, whereas there are considerable alternatives available, if the design and performance criteria are flexible.