A 10x reduction is very doable. Consider this: the Vogtle units 3-4 cost about $37 BN [1]. The similar size Karachi units 2-3 cost about $10 BN [2]. The difference is that the Karachi units were built by China. The design used at Karachi is called Hualong One [3], and since China built the 2 Karachi units, it has built 5 more, and has 15 more under construction and 9 more approved for construction. The cost of the reactors that China builds for itself is not known, but it's very likely lower than the ones that China built for Pakistan.

[1] https://en.wikipedia.org/wiki/Vogtle_Electric_Generating_Pla...

[2] https://en.wikipedia.org/wiki/Karachi_Nuclear_Power_Complex

[3] https://en.wikipedia.org/wiki/Hualong_One