Buying ND filters need some advice! :)

[lerabu]

Hey all!

I am going to buy my frist ND filter and I am looking at options over on eBay, there are some things that I am trying to keep in mind, like whsat is it that I want to achieve?

I love shots where for example the rippling of water has been rendered smooth by a long exposure, or long exposure night shots. I was thinking that the best would be and ND8 filter but here is an interesting option I found on eBay but I would like to ask for your advice regarding image quality:

Slim 72mm Fader ND Filter Neutral Density ND2 to ND400 | eBay

Do you have any experience with faders?

Is there any filter brand you would recommend? I was looking at Nikon filters, Hoya and Kenko. I am trying to strike the balance between quality and price

Thank you in advance for any answers!