Windscreens/ Preventing Gear Noise?

I'm running a Nikon D5100 with a Beyerdynamic MCE S ll Cam set for audio while recording video.

I'm aware auto focus is not preferred when doing video but I do have certain situations that require it, and when I do I get noises from my lens.

I was thinking of getting an 18cm Micover Puffin Wind Diffusion for it, but I also noticed a $30 (compared to $70) windscreen, while Rycote offers an 18cm $110 version.

So my questions:

1. Does the price of the windscreen really matter or is that just because of brand name (should I spend the 70 over the 30 so I don't regret it?)

2. Would a windscreen even help with gear noise?

Keep in mind I have thought of getting other mics and such but its currently out of the question, and yes I have experimented with distancing my mic from the camera, while I could get longer cords the issue lies in that most situations I'm doing everything so my mic needs to be mounted (yes I've looked at adjustable mounts and rigs but I'd rather not buy another rig for the time being, I'm just hoping a windscreen will be a good permanent fix)

1) there may be a 1 or 2 dB difference when using a premium windscreen.
2) noise generated by your camera gear can only be reduced by isolating the microphone from the camera itself

The lens noise is transmitted through the body of the camera, not through the air to the mic. OK, maybe a little to the mic, but it can't be much with an AF-S lens. That is why a lot of point and shoots disable zooming in video… Because the motor noise will drown out everything else.

Take the audio completely off camera, and you won't have this problem.

Windscreens won't help with noise transferred from mounting-that is what a "shock mount" is for. Basically, a shock mount suspends your mic in rubber bands, reducing handling noise that travels through the camera body and mount to the microphone housing.

Having the microphone physically separate from the camera is best, as the vets mention, but a shock mount is the next best thing.