I recently made a $100 error.

My mistake was not over a late payment and overdrawing my checking account, but rather over a toy Nerf gun.

More precisely, one of my kids' Nerf toys that I either accidentally tossed in the trash or gave away to charity. Take your pick; I can't remember.

My youngest asked me to find the Nerf gun in his room and ship it to his new address. I came up empty. That's when I learned on eBay that a replacement might cost around $100, or about five times' what I paid for the toy 10 years ago.

Why the higher price? Amazingly enough, this particular Nerf toy isn't made anymore. Snagged by the laws of supply and demand.

But all this got me thinking: If an ordinary plastic Nerf gun that pumps out foam balls fetches a C-note or more, might I be sitting on thousands of dollars' worth of dolls, GI Joes, Star Wars action figures, Beanie Babies and other toys coated in fine dust in the attic and in the kids' closets?

That was all the motivation I needed for some online research. It was a real eye-opener.

There are hundreds of websites devoted to collectible toys, many with punchy headlines and stories. On eBay, for example, there were 443 listings alone for “rare” toys from the 1990s.

One site I scanned featured “23 toys that are worth a ton of money now.” Another touted how “people are paying hundreds of dollars. ... Get rich!” And then “27 toys you threw out that are worth a fortune now.”

Websites highlighted an original Easy Bake Oven listing for $300, the Classic Super Soaker squirt gun valued at $350, an $840 original Game Boy and a Polly Pocket for $230.

I'm always wary of hype, and your kids should be too if they're seeing dollar signs with the toys they're playing with today or ones put away long ago.

Just because you have a lot of old toys in the attic doesn't mean you'll strike it rich. The value of some of these collectibles — like baseball cards and other items — rides on factors such as notoriety and novelty, rarity, condition and whether the toy is still in its original package.

Pure luck could also spell the difference between a few dollars in your pocket or enough to pay off your kids' student loans. There is definitely money to be made in wheeling and dealing in certain toys just like any other investment, but it's not easy.

The most valuable lessons I learned from my $100 mistake? The toy collectibles market is a game of supply and demand, and a slippery one at that.

Lesson number two: Do not toss your kids toys without asking first. That's why I promise not to touch the Easy Bake Oven that's still in the box until my daughter says so.

Questions, comments, column ideas? Send an e-mail to srosen@kcstar.com.