Members have suggested their favorite sites. Add yours in a reply and we will update the list periodically.
New & Used Cameras, lenses and more:
Adorama – Photography Equipment, Video Gear, and Electronics – New and Used
B & H Photo Video and Pro Audio – New and Used
BorrowLenses – Rent professional photos and video gear – sell used gear
KEH Camera – Buy, sell and trade used camera equipment
Sony Mirrorless Interchangeable-Lens Cameras