Last Halloween, my wife and I sent Radley to school dressed as Sally from "The Nightmare Before Christmas." We'd bought a Sally dress from Little Sleepies, thinking it would work for both the school event and Halloween.

Then we picked a family costume: Radley as Lydia from "Beetlejuice," with us as Adam and Barbara Maitland. It didn't make sense to send her to school in a red dress. Rather than spend more money, we repurposed the Sally dress for school.

Her teachers didn't realize it was a costume, though.

We figured that out later, scrolling through the photos on ClassDojo. In the pictures, it looked like she'd been left out of the festivities. My wife and I were upset.

I learned the hard way that you need a backup costume. So after Halloween, we hit the clearance racks and bought two on sale: Anna from "Frozen," who was Rad's favorite at the time, and Boo from "Monsters, Inc." You never know.

This year, Elsa is Rad's favorite.

And Boo? We watched "Monsters, Inc." with her this past weekend, thinking maybe it would get her excited about the costume. She loves the movie. She even loves Boo. Then I brought her costume out and asked, "Do you want to be her for Halloween?" She looked at it, thought for a second, and said, "No."

When Radley has preferences, she is unapologetic about them. I wonder where she gets that from.

Still, I wanted to know whether this was a Rad thing or a toddler thing.

Developmental psychologists have found that preschoolers struggle to imagine a future self who wants something different. In one study, 3- to 5-year-olds who were made thirsty with pretzels picked water as their snack for tomorrow, even though kids who weren't thirsty overwhelmingly wanted pretzels.

Another study found that 5-year-olds understand their preferences will change, but 3-year-olds don't. Rad isn't even 3 yet. Anna never stood a chance.

Halloween kicks off the spending season, and I would know. I cover a lot of this at my day job as a finance and business writer.

The National Retail Federation releases a report every year on how much people spend on Halloween, and it's wild. This year, shoppers plan to spend over $115 per person, on average. Children's costumes at the stores we checked range from $20 to $45. And families with kids are the most likely to reuse costumes from year to year.

But this strategy my wife and I came up with, buying discounted Halloween costumes the day after the holiday, may be thwarted.

My whole family, including my siblings and Radley's cousins, wants to do a big "Toy Story" theme for Halloween, since there are enough characters for everybody. We go to my brother's in-laws' house every Halloween because their neighborhood really bands together for trick-or-treaters.

It's where we were the Maitlands and Lydia last year, and our costumes were a big hit. I'm thinking "Toy Story" will be a bigger hit, and Radley has already said she wants to be Jessie. She loves her and just met her at Hollywood Studios on our September Disney trip, so no fears there.

I'm worried about school now. Will she wear the Anna or Boo costume? Or do I need to buy an Elsa costume? I'm trying to save money and give you some solid advice here, but I'm struggling myself.

I'll report back after Halloween. For now, this is my dilemma, and I'm sure I'm not alone.

People told me kids are expensive. I knew that when it came to the obvious stuff, like another mouth to feed. But keeping up with a toddler's Halloween costume preferences? That wasn't on my dad bingo card.