Most of my carts have been well used over the last few... almost 20 years (wow I am old) so not quite museum reference as some above seem to have. The EZ4 lite in particular I sliced around a bit to fit in a full size GBA slot so I might have to build it up from what remains of the other cases; it came with white, sky blue (oh the fun we will have with that for Russian translation) and black which you can see split between all of those.
I don't have a EZ4 lite compact (was more like the EZ4 lite deluxe but lacked GBA abilities beyond some small ROMs and instead was geared for DS ROMs instead).
I don't have an EZFlash reform either, missed that boat. EZ3 went some years ago.
If you want more detail of any of them then just ask, can assemble the ones with spare shells as well if necessary.
No need for credit, feel free to share.
Thumbnails so click for larger.
7z also attached with full original res/straight out of the camera with a bonus shot of the first set too in case the forum decides to recode things.
Wonder if we will all be back here in a few months when the DS flash cart catalogue gets sent.
In addition to whatever people can grab from the pocketheaven wiki (most of it was in the internet archive whenever I went looking, though I cared less for flash cartridges) then
http://mootan.hg.to/
https://web.archive.org/web/20150810222526/http://reinerziegler.de/GBA/gba.htm
Some of the old reviews around here will be lacking pictures but archive versions should be available, though you might have to generate the old urls to get there (the various threads link in my signature having a few if simply going by the old index does not work).
https://www.darkfader.net/gba/ does not have much in the way of GBA flash carts but might link to some things that do.
I imagine you went on
http://www.gameboy-advance.net/ long before now but for the sake of others then have a link there.
I did go looking a while back on internet archive* at old GBA flash cart sellers (someone was doubting they cost a lot back in the day) and a lot were in there as well. Jandaman, rbenda.de (later became
http://www.flashlinker-shop.com/ez-flash-iv-minisd-slot-2-gba-gbm-sp-nds-nds-lite-p-443.html ),
https://web.archive.org/web/2006062...ght.com/ds/index.php/Hardware/FlashCartridges
https://web.archive.org/web/2012062...i-Carte-GBA-pour-Nintendo-GBA-DS-DS-Lite.html
https://web.archive.org/web/2009090...atalog/ezfadvance-256m-flash-card-p-1553.html
Opium around here I think it was started a flash cart seller rating thread that might have some old links in that are worth looking at. Edit.
https://gbatemp.net/threads/gbatemps-official-list-of-flashcart-dealers.33039/ , not so many links but hopefully enough to search for and reconstruct things to feed to archives.
gbadev was just about still functioning last time I looked.
https://web.archive.org/web/20070811211454/http://gamebank.jp/
https://web.archive.org/web/20051106021152/http://www.kicktrading.ca/
Sadly most of my old links to Chinese flash cart/emulation/rom/rom hacking sites have died some years ago, and were rarely caught in the internet archive. chinagba.com, yyjoy, tgbus being three of the more noted for me.
Whether you want to see if anything from tehskeen survives on archive.org then you could, though that was more gamecube for most.
Logic sunrise might have a bit as well.
*pro tip for internet archive. Just copy and paste any URL and put something like what is above there. It will auto move to the nearest date it has, sometimes redirecting in the case of "buy this url".
Could probably do links all evening but I have to go make dinner so I will leave it at that.