Gaggia Classic Pro Brew & Steam PID Kit Upgrade with Flow Control, Pro-Level Espresso Upgrade Kit, Gaggia Classic Evo Pro - Kit Only, Machine Not Included - Walmart.com
PID KIT for Gaggia Classic Pro & Classic & Home w/ pre-infusion [KIT-GGP] - $199.50 : Auber Instruments, Inc., Temperature control solutions for home and industry
TopBox PID Mounting System
DIY PID for my Gaggia Classic : r/gaggiaclassic
PID Retrofit KIT for Gaggia Classic - European Model RI9403 [KIT-GGX-EU] - $149.50 : Auber Instruments, Inc., Temperature control solutions for home and industry
Added PID to my Gaggia Classic Pro for a fraction of what the kits sell for. Please read my comment! : r/espresso