Best but inexpensive lens for nikon d5100?

I would like to know if there's any lenses for nikon d5100 that is inexpensive but has a good quality. I'm a university student, I always bring my nikon d5100 with its 18-55mm lens and I love to take pictures like landscapes, buildings, night, and portrait.

I just got the Nikon 50mm 1.8g and i love it. It retails for about $220. Its Way sharper than the 18-55mm and has a larger aperture so it works better in low light. The cons are you can't zoom, your stuck at 50mm so you can't really take it to the zoo or anything. Also it tends to distort the face if you do a really close up vertical portrait.research it on youtube.

I would recommend two options
1. Nikkor 35mm 1.8 G - inexpensive, but sharp with beautiful bokeh (blurred background when wide open) - it is the effective angle of 50mm on the full frame, what makes it most versatile fixed lens

2. Nikkor 18-105 mm - very useful zoom range, though distortion visible on the wide side of the range, it has good VR (vibration reductuion)