cheap mics are varying in quality, it's always good to check a mic for quality and buy from brands who notoriously have good quality.
When looking for a mic i strongly urge you do your research before hand. Some of the bigger brand names who sell cheaper mics will have short lifespans, or bad quality and as mouse mentioned above a bad quality mic can make you sound like a duck. Even phones have differing quality mics, more expensive phones generally give better sounding audio, whereas cheaper phones can and will pick up anything and everything around you; dog barking two doors down? your mic will pick that up, roommate watching TV down the hall? your mic will pick that up. So really my only advice is to do your research before you just go out and buy the cheapest or the most expensive options. There are good mics that you can find for cheap, and there are bad mics that are expensive, it's all a matter of finding what you like and making sure it's not just the factory reject line of products.

-P