I have just built a 30x10 matrix using a 5m long ws2812 strip / 60 LEDs per meter - that is 300 LEDs:
https://www.amazon.co.uk/dp/B088BPGMXB?psc=1&ref=ppx_yo2ov_dt_b_product_details
I split the strip in segments of 10 (which is what these strips really are, as you will see they are joined at every 10th).
Eventually I will add another 30x10 set to make it 30x20 when my monthly pocket money will come in 