Cheap or expensive ND filters for a GoPro

I want to buy some ND filters to make my mountain biking footage look more realistic, faster and better. I found some cheap ones on Ali Express for 25€ and on every other tech site that I looked they were 92€, 129€ and there were ones for 35€. The more expensive ones are made by Polar Pro and it says the glass is made of CinemaSeries glass that has 16 layers of coating.

Does anyone have experience buying cheap ND filters? Is there a noticeable difference between cheap and expensive ones, are they worth it?