Hello Justin,
Step rings can cost around $30 or more, or, less than $10 at places like Samy’s Camera on the West Coast for generic versions.
The link you show, is DOA.
The ND Fader is what you want to add to the gear correct? These are not the same as the ND Filter (AKA Grad) which have a horizon line across the filter used to try and separate bright sky, or sea, salt flats etc. from the rest of a composition.
The ND Fader, is two filters, one which rotates (Polarizer) allowing for a 4 to 8 stop adjustment in collected light and are a must for field or studio capture in HDslr video.
Prices spread across a range and (I’m not certain) but they vary based upon glass/plastic optics and brand.
I bought the largest one to fit my 70-200 and 24-70 which thread at 77mm, but instead of buying the same brand (Genus) filter adapter rings, I bought generics for the other threaded lenses, 52, 58, 62, and 67 which cover our lens locker generally.
The Genus company are fine folks, but on a budget I purchased Kenco adapters all five for about the price of a single Genus.
Not sure what those differences are, perhaps aircraft grade aluminum or something like that.
Also, if you buy in a store, be sure to make the selection for step up or step down, as there are both and not all sales folks know which is which.
If I’ve stated the obvious on the subject, it’s because the link would not fly, hence the explanations. Besides, I was chasing around another forum using the incorrect nomenclature and just wanted to be sure you meant ND Fader.
HTH’s,
Rob