Reddit mentions of Nikon AF-S DX NIKKOR 18-55mm f/3.5-5.6G Vibration Reduction II Zoom Lens with Auto Focus for Nikon DSLR Cameras

Honestly, that's kind of a high price for a used 18-55. For what it's worth I recommend the latest VR version, partly for the better VR and more compact size, but also because it really does seem to be sharper than earlier versions of the lens. For a 24 megapixel camera you can actually see that difference if you are using good technique in favorable conditions.

In case the price tag didn't tell you, that 14mm is a pretty serious lens! Unfortunately with the 1.5x crop factor it's not going to be that wide on that body, and you'd want an FX body to make the most of it. If you like wide angle, I recommend sticking with FX lenses and quickly switching to an FX body... or sell that lens for a good price and use it for DX upgrades.

I am looking to buy a cheap variable nd filter and polarizing filter for my NIKKOR 18-55mm lens. The polarizing filter I am looking at is the Tiffen 52mm Circular Polarizer. I'm still not sure which nd filter to get. Should I get the ZOMEi ND2-ND400 or the Polaroid Optics ND filter?

7200 is a great choice! 18-55 for landscape, 55-300 for wildlife, 35 1.8 DX for crispy shots and bOkeh and some extension tubes for macro. You'll see later whether you want spend thousands for better pro lenses. For start this should cover almost everything.

I broke my kit lens that came with my d3100, so I'd like to replace it. Are all these lenses the exactly the same?

Amazon, eBay, Amazon Refurb

There is a considerable price discrepancy between the two new items ($247 vs. $96). The eBay seller seems reputable.

I'd recommend a lens with a wide zoom range. For lifestyle-type shots where you are shooting yourself/your friends/the journey from a more intimate perspective (read -- up close) and the occasional landscape, I'd recommend a lens that gives you at least a 18-24mm focal length at the bottom end. It's hard to take pictures of the car or your friends with a 200mm telephoto lens, unless you want an up close and personal shot of the pores on your friends' noses.

My 18-135mm kit lens that came with my Canon works wonderfully for me when I'm on trips. It's very versatile. The lens that I'm referring to is this (this is a CANON lens, it won't fit your Nikon):
https://www.amazon.com/Canon-EF-S-18-135mm-3-5-5-6-Lens/dp/B008UGMLWQ/ref=sr_1_1?ie=UTF8&qid=1500062853&sr=8-1&keywords=canon+18-135

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Alternatively, for YOUR particular camera, I'd recommend something like this Sigma 17-50mm:
https://www.amazon.com/Sigma-17-50mm-Aperture-Standard-Digital/dp/B003A6NU3U/ref=sr_1_1?ie=UTF8&qid=1500062448&sr=8-1&keywords=sigma%2Bcanon&th=1

The latter lens has a shorter zoom range (17-50mm) than my Canon lens that I mentioned, but you get a nice, low aperture of f/2.8 throughout the entire zoom.

A cheaper option that is similar to the Sigma lens that I mentioned above is a Nikon lens that can be found here:
https://www.amazon.com/Nikon-18-55mm-3-5-5-6G-Vibration-Reduction/dp/B00HQ4W4PC/ref=sr_1_2?ie=UTF8&qid=1500062981&sr=8-2&keywords=nikon+lens+18-55

The Nikon lens listed has a variable aperture, and the lowest that it will go is 3.5. I'd spend the extra ~$100 and get the Sigma lens. You'd probably get a TON of use out of that Sigma for a long time.

Please feel free to reach out if you have some more questions. :-) There are some great people here.