Amazon.com: for ATMEL 51 AVR USB ISP ASP Microcontroller Programmer Downloader with Cable + 10Pin to 6Pin Adapter Board for Ender 3 or Ender 3 Pro Geekstory : Electronics
Standalone AVR ISP Programmer Shield Kit - includes blank chip! : ID 462 : $17.50 : Adafruit Industries, Unique & fun DIY electronics and kits
Pololu USB AVR Programmer
USBtinyISP AVR Programmer Kit (USB SpokePOV Dongle) [v2.0] : ID 46 : $22.00 : Adafruit Industries, Unique & fun DIY electronics and kits
Standalone AVR ISP Programmer Shield Kit - includes blank chip! : ID 462 : $17.50 : Adafruit Industries, Unique & fun DIY electronics and kits
Pololu USB AVR Programmer
Amazon.com: for ATMEL 51 AVR USB ISP ASP Microcontroller Programmer Downloader with Cable + 10Pin to 6Pin Adapter Board for Ender 3 or Ender 3 Pro Geekstory : Electronics