There's a bunch of ID75 shoe options(since ID75 is pretty popular now), usually if you find something a little bigger than 9.5 cm, it should fit. I bought my shoes from etsy here: BJD 1/4 70cm 1/3 ID75 HID in Stock Chelsea Boots Black White Brown SD17 AS74 Shoes - Etsy BUTTTT it might be cheaper if you find and buy it on Taobao. Just make sure when shoe shopping that the length is bigger than 9.5 cm and wider than 4.3 cm.
I got mine off eBay, just pay attention to the measurements when ordering. He has a foot length of 9.5cm so a 10cm shoe will fit him. I bought 10cm shoes for mine.