http://starwarshelmets.com/ is a website where you can find a lot of images with various screen used, but also licensed and fan made helmets, Jez knows a lot about lids, there are even a few of my own reviews there. Then there is
http://www.partsofsw.com/, with cool information about sabers, blasters and other props, though not updated and the images are small. There are also forums like RPF, Prop Den, 501st, and of course FB groups that discuss all kinds of props and models.
I own a huge archive of thousands of images (about 12 GB) of various screen used Original Trilogy props, lightsabers, blasters, helmets, costumes, armors, studio scale models etc., from Imperial stuff like Vader, Stormtroopers, Snowtroopers, Scouts, Sandies, Royal Guards, Emperor, Pilots & Drivers etc., all of the TIE fighters, Imperial Shuttle, Star Destroyers, Death Star, AT-AT and AT-ST, to rebels, droids, aliens, and bounty hunter stuff: Millennium Falcon, Tantive 4, Slave 1, X-Wing, Y-Wing, A-Wing, Medical Frigate, Cloud Cars, all kinds of speeders, robots and droids, costumes, set dressings, obscure props, and of course Luke, Obi and Vader lightsabers etc., you name it.
Some images were never shown to the public, as I do not have the permission, but even so the rest of the archive is immense. I used to have a Photobucket account, with many of these images, I posted that link on this forum and others for free, so people could see most of those images, but when Photobucket went rogue, I deleted them all and uploaded them, folder by folder, with a lot of new images and updates, on another hosting site.
Drop me a PM and I might send you the new link. I will not post it here anymore.