We research all brands listed and may earn a fee from our partners. Research and financial considerations may influence how brands are displayed. Not all brands are included. Learn more.

Money is not a client of any investment adviser featured on this page. The information provided on this page is for educational purposes only and is not intended as investment advice. Money does not offer advisory services.

Lego Value Investing
Ratcliffe, Chris—Bloomberg/Getty Images

Lego is a beloved toy brand, not an investment vehicle that's part of many people's portfolios. Only, maybe it should have been. Since the year 2000, the Danish building blocks have actually appreciated better than numerous investments.

In the last 15 years, the average value of a Lego set has gone up, with "pristine condition" sets appreciating 12%, according to the Telegraph, which added that prices jump when a model is discontinued, and that sets from last year are up around 36%.

This kind of return is incredible. In that same span, the S&P 500 has returned about 4.2% annually, gold 9.6%, and the the U.K.'s FTSE 100 is about the same as it was at the turn of the millennium.

Read Next: Gold Isn't a Good Investment

Products in highest demand are specialized sets like Star Wars editions, but apparently everyday versions are still highly sought after, according to the Telegraph, which crunched the numbers from Lego enthusiast site BrickPicker.com, which in turn crunches eBay's numbers. The Internet auction site is the most common trading ground for rare and discontinued models. And since Lego is constantly retooling its offerings, the exchange is healthy.

With numbers like 36% being thrown around—and articles like this being written—it's hard not to see some bubble-like characteristics at play. But BrickPicker.com's founder told the Telegraph this isn't the case, "partly because the Lego company doesn't promote the secondary market, it wants to sell direct to customers."

Read Next: Harrison Ford Will Earn 3,400x More for 'Force Awakens' Than the Original 'Star Wars'

Though Lego sets have great returns, it's not necessarily realistic to add Legos to your portfolio, given the legwork involved in buying and reselling, as well as keeping tabs on the market. But like a Rolex, it might not be a bad idea to dabble with a set or two, if you're into Legos. Besides getting a sweet toy to play with, it could be worth something later.

Here's the top five most expensive sets currently:

1. Ultimate Collector's Millennium Falcon: $510 in 2007, now $4,041

2 Cafe Corner: $134 in 2007, now $3,123

3 Taj Mahal: $298 in 2008, now $2,753

4 Death Star II: $372 in 2005, now $2,270

5 Imperial Star Destroyer: $249.99 in 2002, now $2,185