Electrodragon is selling ESP32-Wrover V4 Module at a price of 4 US$ (3.6 US$ if you register) + < 3 US$ shipping. I makes it cheaper than most of the ESP32-WROOM modules.
Combined with a <2 US$ ESP32-WROVER Breakout Board, <1 US$ power supply (linear or Switching) and some ~1 US$ USBtoSerial, it makes very cheap development board for testing psRAM features.