Hello, If you are looking for level readers I purchased a box of them. They are all hardbacks and in almost new shape.

Tony's Birds/Selsam

Authur's Christmas Cookies/Hoban

No Funny Business/Hurd

Binky Brothers Detectives/Lawrence

Stanley/Hoff

Oliver/Hoff

Piggle/Bonsall

Red Tag Comes Back/Phleger

The Case of the Hungry Stranger/Bonsall

The Case of the Cat's Meow/Bonsall

Donald and the Fish that Walked/Ricciuti

A Bargain for Francis/Hoban

Plenty of Fish/Selsam

An Animal for Alan/Ricciuti

Binky Brothers and the Fearless Four/Laurence

The Homework Caper/Lexau

Arthur's Prize Reader/ Hoban

Jelly and the Spaceboat/Parenteau

Hattie Rabbit/Gackenbach

Gink and Pearl/Cherae

Uncle Elephant/Lobel

Bony/Zweifel

Mooch the Messy/Sharmat

McBroom Tells the Truth/Fleischman

Twelve Bells for Santa/Bonsall

Busy Buzzing Bumblebees and other Tongue Twisters/Schwartz

Hattie, Tom, and the Chicken Witch/Gackenbach

Ottie and the Star/Allen

Scarlet Monster Lives Here/Sharmat

Come Back Amelia Bedelia/Parish

Morris is a Cowboy, a Policeman, and a Baby Sitter/ Wiseman

Hurry, Hurry/Hurd

No Fighting, No Biting/Minarik

Red Fox and his Canoe/Benchley

Six Silver Spoons/Lowrey

If you have any questions please PM me! 

Books I can't find a ISBN for are:

Morris is a Cowboy, a Policeman and a Babysitter by B. Wiseman

Good Luck Liz by Bill Wallace

Hurry, Hurry by Edith Thacher Hurd

Old Stories from Denmark  by Elles Boghandel

At the Zoo by Anne Heath

Dolly

Unpostable: Warriors Twilight to someone that orders three books or more.