Do you need a seriously cheap USB camera for remote machine monitoring or other low resolution tasks? Have a look here. This camera and lens combo cost me $4.81 and included free shipping.

The camera is an OV7675 module commonly used in laptops and other compact applications. The resolution is 0.3MP (640x480), which is adequate for my need to monitor multiple (4 or more) machines, with all cameras streaming through a single RasPi 4.

Yes, it's potato for sure, but I don't need more than that for my application.

BOM

Fisheye Lens, Qty 1 (Search for: High Quality Clip 180 Fish Eye Smartphone Professional Cinema Quality Wide Angle Lens Cell Phone)

Camera Module, Qty 1 (Search for: USB OV7675 Camera Module 66 Degree View USB Frees Driver Webcam 1/6.5" YUY2 Focal Adjustable)

Cheap CMOS Housing - Back, Qty 1 Cheap CMOS Housing - Front, Qty 1

M5x6x7 Heatset Insert, Qty 1 M2x10 round head tapping screw, Qty 2 M2x4 round head tapping screw, Qty 2

Assembly Notes

Install the M5 heatset insert from the front, into the enclosure back (see photo of the back of the enclosure, showing the insert installed from the opposite side)

While the plastic is still warm, run a 20mm M5 down the insert to form the threads behind the insert

M2x4 self tappers are used to hold the board down; M2x10 are used to attach the front plate to the back housing

The thread in the front plate is M18x1, and the lens is threaded M17x1. Yes, it works fine