“Yo mama’s so stupid, she asked for a price check at the 99-cent store”

Everyone knows that all items in a dollar store (or a 99-cent store) cost one dollar (or 99 cents), although very often selected items have different prices. A popular “yo mama joke” (cited in print since at least 1994) is:
 
“Yo moma’s so stupid, she asked for a price check at the 99 cent store.”
 
The joke also became a “dumb blonde” joke by the late 1990s. “SHE WAS SO BLONDE…she asked for a price check at the Dollar Store” was cited in print in 1998.
     
 
Google Groups: rec.humor
Yo Mama Jokes
Erick Ramos
7/14/94
(...)
Yo moma’s so stupid, she asked for a price check at the 99 cent store
   
Google Groups: rec.humor
Yo Mama
Barry
9/21/95
(...)
Yo mama so stoopid she has to ask for a price check at the 99 cent store.
 
Google Groups: rec.food.cooking
LONG: I though THIS group was close…
ALZELT
9/12/98
SHE WAS SO BLONDE…..............
(...)
- she asked for a price check at the Dollar Store
     
Google Groups: rec.autos.sport.nascar
I agree with Henry, Lick Bush in 2000
Tat
3/10/00
(...)
How blond was she ?
She was sooooooooooooooo blonde,
(...)
She asked for a price check at the Dollar Store.
 
Google Books
Double Dutch
By Sharon M. Draper
New York, NY: Atheneum Books for Young Readers
2002
Pg. 6:
Randy grinned and yelled back, “No, but I saw your mama there. She’s so backwards, she was askin’ for a price check at the dollar store!”
 
Google Books
Yo Mama Jokes - 555 Funny Insults: The New And Best Ones:
Illustrated Edition
By Mature Jokemaker Jr.
eins zum anderen Media Verlag GmbH
2014
Pg. ?:
Yo mama is so stupid that she asked for a price check at the dollar store.