Companies such as ST Microelectronics, Hitachi, NXP Semiconductors, Ti, Infineon Technologies and many others make devices for ISO15693 vicinity cards. Between the data sheets, and code examples there is a wealth of information on the manufactures sites and forums. There are also low cost eval boards with reference designs and example software. Since it is a slow and somewhat simple protocol it is easy to simulate and can be easily bit-banged with a low performance MCU.