Amazon has some. Not sure if you want lined or dot grid.

A5 Dot Grid Paper, Extra Thick, 6-Hole Punched, 200 Sheets (400 Pages), 120 GSM https://www.amazon.com/dp/B0848HSTY7/ref=cm_sw_r_cp_api_glt_fabc_BFHQKPDNDZHCSNKRQNCH?_encoding=UTF8&psc=1

I got this from Amazon, and I am very happy with the quality.