Shelter or Breeder?

Question
HI! So im 11 years old, and my mom is thinking of buying a chihuahua pup :
Me : *looks for chihuahua pups on sale* mam! wanna applehead?
Mam : yep, wait. if you really want a pup we could just go to the shelter! what was that dog's name? Decko?
Me : YUP!
so  Decko was a black full grown chihuahua at the shelter. and i was obsessed with him!
so i was debating if i should continue browsing sites for breeders, OR if we should just take a trip to the local shelter and examine some pups. most likely i would like to adopt. but would the newly adopted dog be aggressive, gnarly, snappy, and yappy toward us? what if we get a young'un? in which hasnt been through much physical and/or verbal abuse?
sorry for not stating one "on the point" question.

Answer
If you *really* want a chihuahua, then go to a reputable breeder who not only breeds to a breed standard in regard to appearance, but also breeds for health and good temperament, too. http://www.chihuahuaclubofamerica.com/breed-info/cca-breeder-directory

Rescue can be a good way to find a great pet, but one must always remember that those dogs ended up in a rescue or shelter for a reason, and some may require a LOT of work to turn them into nice pets.

Also, many shelters/rescues slap a breed name on a dog because, in someone's mind, there is a certain breed resemblance there... or mix of breeds. A purebred chihuahua should not exceed 8 lbs.