#1
Are there any decent ones for that price?
Amps:
Fender Frontman 15r

Guitars:
Epiphone Dot Studio
Squier Strat

Pedals:
Crybaby Original Wah
Boss DS-1
#2
you might be able to search a bunch of pawn shops and find something worth while
"Spin the middle side topwise. Topwise!"

"And there's Jimmy Page, the biggest thief of American Blues music"
#4
The Jasmine line by Takamine makes a few models for around $130. Anything less will end up being a waste of time and money.
#5
I started on a Kay from a pawn shop for around 50 bucks. That was a LONG time ago though. Mom likely doesn't want to invest a whole lot for legit reasons. If your brother ends up getting the cheap department store model and loses interest then there is nothing really lost.

You might also be able to get something on Craigs List or Kijiji. I would try used and get what you can. If not then at least he has something which is better than no guitar at all.

I mentioned in another thread that it's not so much the guitar as it is the player. I once saw Clint Black pick up a cheap plywood guitar and he made that thing sound beautiful.
#6
no. any guitar your mom spends $100 or less on will be a toy or a piece of junk. they sound crappy, are usually poorly built and are harder to play. importantly enough, unless your brother is HIGHLY motivated to learn, these guitars are likely to make him quit.

if you are lucky enough to live in the los angeles area, your mom can rent a guitar for 3 months at mccabes - something decent like a seagull. otherwise you might want to show her this:

http://www.mccabes.com/rentalpolicy.html

the beginning of it explains why not to buy a cheap guitar clearly.