First tell us what equipment you have access to.
The cheepest thing to use, if you have a windows computer and within listening distance is to use a program called DSD+ that needs the audio from the transmission being feed into the line in audio jack of the computer. You can get an SDR tv/radio USB dongle for $10 that also will feed it's audio directly to the program.
You also have the option to get a $100 TYT MD380 radio that you program with a new firmware that lets you listen, decode and display all data of a DMR frequency you program in the radio.
/Ubbe