They are on amazon.com (i.e. the US site). Don't think prime works but shipping is still way better. For reference, to the UK, its $23.33 for shipping on the DDLC store but $5.20 on amazon.

https://www.amazon.com/Doki-Literature-Club-DDLC-Monika/dp/B07Q4QYK64/ref=mp_s_a_1_1?keywords=Monika&qid=1566226555&s=gateway&sr=8-1 This might help.

https://www.amazon.com/gp/aw/d/B07Q4QYK64/ref=ya_aw_od_pi?ie=UTF8&psc=1