I see nothing special about their photography. Maybe their photography is better on a magazine if they have one.
Go to Nikon, Tamaron, Sigma and Tonica websites and see what they offer.
Fisheye will be tough as your camera will multiply the focal length by 1.5x ... so you are probably looking at a 10mm lens to give you 15mm.
Close up is probably 35mm to give you "normal" lens view (50mm). I am assuming you're not talking macro.
Coverage shots, look at zooms. They allow you to stand in one place and get the look you're after. Or else look at 85mm, 105mm, 135mm, 200mm and 300mm prime lenses.
Better quality lenses usually have larger f stops (2.0, 1.8 or 1.4). Larger f stops = more money.
But with all that said, having decent (or great) gear may not give you better results. Learning to really use what you have right now will probably give you the same or better results that are on that website.
Just my opinion!