I would have to recommend Neewer for their ND faders, AKA variable ND filters. I got a 52mm thread one for my Canon 50mm 1.8 II and love it so much, it only cost $5 with another $5 for shipping, I would say I have gotten a lot more use out of it then $10. Just one photo using it earned me enough money to buy over 10 of them. It does not reduce sharpness all that much, it is almost unnoticeable, you are more likely to lose sharpness from your subject or your tripod moving slightly. My only complaint about it is that it changes from a 52mm thread to a 54mm thread so I can't put on my hood for my 50mm but most lenses have another mount for their hoods so this isn't even that much of a problem. Here is a link to the 77mm Neewer ND fader on Amazon for $11.32, http://www.amazon.com/NEEWER%C2%AE-Neutral-Density-Adjustable-Variable/dp/B0059ATVJW/ref=sr_1_1?ie=UTF8&qid=1345425685&sr=8-1&keywords=neewer+77mm
. Neewer does a great job of making ND faders and I would recommend them to anyone because of their cost and performance. You might have to do a little bit of color correction in post but that is something you should do no matter if you have the filter on or off and at high densities it suffers from weird pattern problems, but not worse then $400 ND faders, if anything better then them.
Here is just one of the amazing shots I've gotten from this great filter
Also, love the name, I've got a '11 GTI, LOVE the sound of a VR6, what is it in?