Hi Ellie,
If your story has more words than a PB (less than 500), you're probably talking about early chapter books/transitional chapter books vs. early readers, which can have as few as 20-80 words and are for those just beginning to read. Is your audience 2nd-3rd graders?
Can you borrow books via WorldCat through your library? I do that when my library doesn't have a particular title. You might look into Diary of a Wimpy Kid (not fantasy), Princess in Black (love), Dragon Masters (Scholastic), Dragon Slayers' Academy, or Big, Bad Detective Agency.
Good luck!
Jody