Well, anon... Here isn´t a good place to make deals. However, there are good sites to buy doujinshi, for example. Have you tried Otaku Republic? Their prices can be a bit high, but you can ask them for any doujinshi you want.
This is their Oumami section:
https://otakurepublic.com/product/danganronpa_v3%3A_killing_harmony/tag_page.html?tags=236315,493105&ref=tag_pageHope it helps a bit!
