I have a lot of original Dreamcast games, here is a
link to a rar containing my own scans, 256x256.jpg, some admitably were downloaded from covergalaxy, which was only a couple the rest are from my own scans.
Still have some scanned that need touch ups and stuff, the majority of my collection still remains un scanned, maybe one day, its not that easy as usa and jap games don't have front covers, they have manuals, the only way to do them properly is take the staples out, flatten the manual and scan each page both sides, or do a quick scan of the front of the manual, which is probably going to be fine for 256x256.jpg, but you would still be better off doing it the other way that is more hassle.
I mainly have more JAP then PAL then USA games, I once went some were that sold computer stuff and had stalls were people went to sell stuff, and a bloke was selling factory sealed jap games for next to nothing, I got as many as I could which was about 100 games, and I must have bought 100 since then from ebay and places, a lot of dupes of certain games unfortunately. Some still factory sealed