Developers of some open source photography software have set up a nice site
https://pixls.us/As part of this, they maintain a collection of raw samples:
https://raw.pixls.us/They would like samples of CHDK DNG and framebuffer dump (CRW/CR2) for any cameras not already in the database. Native Canon raw and raws from other manufacturers are also welcome.
Details are described on the page but briefly:
* Only one sample of each format is needed for a given model
* Image must be licensed CC0
* It should be straight from the camera without any modification
* It should be portrait orientation, in focus, not totally dark or blown out. Generally a normal, recognizable image
* Should not contain images of people
* For CHDK DNG, use DNG 1.3.
If you have a camera there isn't already a sample for, please contribute. You can type Canon in the search box to see which cameras they already have samples for.
If you upload samples, please also post which models you uploaded here, to save time and duplication.
I have uploaded sample from my cameras
* D10
* IXUS140 / ELPH130
* A540
* SX160
* G7X