Walmart has several children's Halloween books marked down, including several board books. Shipping is free with Walmart+ or on orders over $35.
Sticker Friends (300 Reusable Stickers) - $1.18 (https://www.walmart.com/ip/Sticker-...Paperback-9780312520205/49744812?athbdg=L1600)
The Night Before Halloween (Paperback) - $1.18 https://www.walmart.com/ip/The-Night-Before-Halloween-Paperback-9780448419657/682914
The Berenstain Bears Trick or Treat (Paperback) - $1.18 - https://www.walmart.com/ip/The-Berenstain-Bears-Trick-or-Treat-Paperback-9780679800910/379028
The Itsy Bitsy Pumpkin (Board Book) - $1.42 - https://www.walmart.com/ip/Itsy-Bitsy-Pumpkin-Board-Book-9781481405058/30526378?athbdg=L1100
Peanuts The Legend of the Great Pumpkin (Board Book) - $1.42 - https://www.walmart.com/ip/Legend-o...oard-Book-9781481496285/55743980?athbdg=L1100
Corduroy's Trick or Treat (Board Book) - $1.42 - https://www.walmart.com/ip/Corduroy...Board-book-9780670035625/1748095?athbdg=L1100
There Was an Old Lady Who Swallowed a Bat! (Paperback) - $1.57 OOS https://www.walmart.com/ip/There-Was-an-Old-Lady-Who-Swallowed-a-Bat-Paperback-9780439737661/3934071
Where's Boo? (Board Book) - $1.57 - https://www.walmart.com/ip/Where-s-...oard-Book-9780307978080/22267389?athbdg=L1100
Five Black Cats (Board Book) - $1.57 - https://www.walmart.com/ip/Five-Black-Cats-Board-Book-9781589252394/52703167
PJ Masks: Five Little Ninjalinos (Board Book) - $1.57 - https://www.walmart.com/ip/5-Little-Ninjalinos-A-Halloween-Story-Board-Book-9781534417830/492368348
Trick or Treat Baby Shark (Paperback) - $1.57 OOS - https://www.walmart.com/ip/Trick-or...-Doo-A-Book-Paperback-9781338665307/558401162
Where is Baby Pumpkin (Board Book) - $1.79 - https://www.walmart.com/ip/Where-Is-Baby-s-Pumpkin-9781416909705/4455453?athbdg=L1100
Boo (Board Book) - $1.79 - https://www.walmart.com/ip/Boo-Board-Book-9781680105018/45687890?athbdg=L1100
Room on the Broom (Board Book) - $1.79 - https://www.walmart.com/ip/Room-on-...rd-Book-9780803738416/19483950?isPACOpen=true
Dreamworks Trick or Trolls (Board Book) - $1.79 - https://www.walmart.com/ip/Trick-or-Trolls-DreamWorks-Trolls-Board-Book-9780593127810/561458085
5 Little Pumpkins (Board Book) - $2.01 - https://www.walmart.com/ip/5-Little-Pumpkins-Board-Book-9781589258563/14257483?athbdg=L1100
Paw Patrol: Puptastic Halloween (Board Book) - $2.02 - https://www.walmart.com/ip/Paw-Patr...-Flap-Book-Board-Book-9780794439651/762525029
I Love You, Little Pumpkin (Board Book) - $2.03 - https://www.walmart.com/ip/I-Love-You-Little-Pumpkin-Hardcover-9781338110852/55495885?athbdg=L1100
Mickey & Minnie Scaredy Mouse (Board Book) - $2.24 - https://www.walmart.com/ip/Scaredy-Mouse-Board-Book-9780794441623/726948861?athbdg=L1100
Chunky Pack: Halloween (Board Book) - $2.49 - https://www.walmart.com/ip/Chunky-Pack-Halloween-Board-Book-9780312518516/45144454
Many more (complete list sorted by price): https://www.walmart.com/browse/hall...s/3920_4640285_9564915_7090388?sort=price_low
Sticker Friends (300 Reusable Stickers) - $1.18 (https://www.walmart.com/ip/Sticker-...Paperback-9780312520205/49744812?athbdg=L1600)
The Night Before Halloween (Paperback) - $1.18 https://www.walmart.com/ip/The-Night-Before-Halloween-Paperback-9780448419657/682914
The Berenstain Bears Trick or Treat (Paperback) - $1.18 - https://www.walmart.com/ip/The-Berenstain-Bears-Trick-or-Treat-Paperback-9780679800910/379028
The Itsy Bitsy Pumpkin (Board Book) - $1.42 - https://www.walmart.com/ip/Itsy-Bitsy-Pumpkin-Board-Book-9781481405058/30526378?athbdg=L1100
Peanuts The Legend of the Great Pumpkin (Board Book) - $1.42 - https://www.walmart.com/ip/Legend-o...oard-Book-9781481496285/55743980?athbdg=L1100
Corduroy's Trick or Treat (Board Book) - $1.42 - https://www.walmart.com/ip/Corduroy...Board-book-9780670035625/1748095?athbdg=L1100
There Was an Old Lady Who Swallowed a Bat! (Paperback) - $1.57 OOS https://www.walmart.com/ip/There-Was-an-Old-Lady-Who-Swallowed-a-Bat-Paperback-9780439737661/3934071
Where's Boo? (Board Book) - $1.57 - https://www.walmart.com/ip/Where-s-...oard-Book-9780307978080/22267389?athbdg=L1100
Five Black Cats (Board Book) - $1.57 - https://www.walmart.com/ip/Five-Black-Cats-Board-Book-9781589252394/52703167
PJ Masks: Five Little Ninjalinos (Board Book) - $1.57 - https://www.walmart.com/ip/5-Little-Ninjalinos-A-Halloween-Story-Board-Book-9781534417830/492368348
Trick or Treat Baby Shark (Paperback) - $1.57 OOS - https://www.walmart.com/ip/Trick-or...-Doo-A-Book-Paperback-9781338665307/558401162
Where is Baby Pumpkin (Board Book) - $1.79 - https://www.walmart.com/ip/Where-Is-Baby-s-Pumpkin-9781416909705/4455453?athbdg=L1100
Boo (Board Book) - $1.79 - https://www.walmart.com/ip/Boo-Board-Book-9781680105018/45687890?athbdg=L1100
Room on the Broom (Board Book) - $1.79 - https://www.walmart.com/ip/Room-on-...rd-Book-9780803738416/19483950?isPACOpen=true
Dreamworks Trick or Trolls (Board Book) - $1.79 - https://www.walmart.com/ip/Trick-or-Trolls-DreamWorks-Trolls-Board-Book-9780593127810/561458085
5 Little Pumpkins (Board Book) - $2.01 - https://www.walmart.com/ip/5-Little-Pumpkins-Board-Book-9781589258563/14257483?athbdg=L1100
Paw Patrol: Puptastic Halloween (Board Book) - $2.02 - https://www.walmart.com/ip/Paw-Patr...-Flap-Book-Board-Book-9780794439651/762525029
I Love You, Little Pumpkin (Board Book) - $2.03 - https://www.walmart.com/ip/I-Love-You-Little-Pumpkin-Hardcover-9781338110852/55495885?athbdg=L1100
Mickey & Minnie Scaredy Mouse (Board Book) - $2.24 - https://www.walmart.com/ip/Scaredy-Mouse-Board-Book-9780794441623/726948861?athbdg=L1100
Chunky Pack: Halloween (Board Book) - $2.49 - https://www.walmart.com/ip/Chunky-Pack-Halloween-Board-Book-9780312518516/45144454
Many more (complete list sorted by price): https://www.walmart.com/browse/hall...s/3920_4640285_9564915_7090388?sort=price_low