BTW, Deco X20 is the low end dual band AX1800, Deco M9+ is high end tri-band AC2200, if using wireless backhaul, M9 + is still better. So it is quite understandable that X20 is cheaper.
But if one understands Chinese and okay to go with the cheaper China routers, then there are more cheaper WiFi 6 mesh solutions from Taobao.
Eg: Huawei AX3 Pro + AX3, RMB329+RMB229
Or this one from TP-Link, XDR-1850 AX1800, the design looks not bad if you want something more Mesh look than the above Huawei. RMB219 per piece.
https://m.tp-link.com.cn/product_1689.html
Nice.. How to use two routers and create their own mesh network?