The radios were seen only in GB1 and there are two models that are used. Peter and Egon are seen with the Motorola MT-500. These radios are vintage now, though come up quite regularly on ebay. The correct model has three dials on the top of the radio, the radio body is the older, longer model and has a short, stubby antenna. Any MT-500 variant is acceptable though. Ray uses a similar radio, a Motorola HT-220. Which variant of the HT-220 he uses is hard to discern, some models have a keypad on the front similar to a mobile phone. Any HT-220 is also acceptable.
MT-500
HT-220
The video game also introduced a new radio worn on the left pack strap. This radio has been identified as the Motorola HT1000, though the MTX838 and GP900 have the same bodies and would be perfectly fine.
Radio holster can sometimes be found on ebay though there are sellers on www.gbfans.com who offer replica holsters made of leather.