Scans are very much preferred, but some items are simply too difficult to scan for various reasons (fragile packaging, uneven shape, glossy / shiny foil art or colors) so photos are fine.
Scans from sites like MobyGames or GameFAQs are also acceptable, as long as the scan matches your item completely. There are lots of variants out there and GameFAQs is really bad at keeping their scans straight (people submit images for the wrong version a lot of times.) And don't forget, any picture you find on the internet should have no watermarks.