Elecom WRC-X3200GST3
Actually sold in Japan, can be found for less than $100
Looks like the same as the already supported elecom_wrc-2533gent + WIFI AX Support.
Current Firmware is based on Openwrt 17.01:
https://dl.elecom.co.jp/support/download/network/wireless_lan/wrc-x3200gst3/WRC-X3200GST3_v1.20.zip
wikidevi confirms : MediaTek MT7622/MT7531
According to the files in the firmware, the wifi is based on MT7622/MT7915
The AC version (WRC-2533gent) has 4Gb Flash and 512Mb RAM, if it's the same for this device then i think it's a good challenger for the Linksys/Belkin RT3200.