Excellent setup and configuration information: https://amateurradionotes.com/pi-star.htm
Information on Rewrite Rules: Rewrite Rules · g4klx/DMRGateway Wiki · GitHub
MMDVM Configuration File Explained: https://on7lds.net/42/node/44
Firmware upgrade for MMDVM Modem: https://amateurradionotes.com/firmware.htm
MMDVM Hat (~$45) : [Amazon](https://www.amazon.com/dp/B07L4SJ521?) - As of 7/22 only recommended if you already have a Raspberry Pi
Simplex Jumbo Spot ($170) Pi-Star Based : Amazon
Duplex Jumbo Spot ($190) Pi-Star Based: Amazon
Zumspot Elite ($250) Pi-Star Based: HRO
openSPOT4 ($285) Proprietary: SharkRF
SkyBridge Plus ($425 and up) Pi-Star Based : Bridgecom Systems
SDCards: SanDisk High Endurance 32gb ($10): [Amazon](https://www.amazon.com/dp/B07P14QHB7?)
balenaEtcher Image Writer - Put an image on an SD card for your Pi
Pi-Star - THE standard interface to your MMDVM