Lots of investments can double your money. Some of them require huge amounts of upfront cash. Many also require a long time to provide that 100% return you want.

There are some investment alternatives, though, that don't need a hefty initial amount and don't take an agonizingly slow period to grow. Here are three stocks you can buy for under $50 each that could realistically double your money over the next five years.

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Cresco Labs

You might have a negative mental picture when you think of cannabis stocks. Many of these stocks are risky and unprofitable. Some are downright sketchy. However, Cresco Labs (CRLBF -4.76%) doesn't belong in that group.

Cresco ranks as the No. 1 cannabis wholesaler in the U.S. It's also one of the top multi-state cannabis operators with more than 30 retail locations in 10 states, including seven of the top 10 biggest markets. 

The company is profitable. Its sales soared nearly 123% year over year in the second quarter. Cresco expects to have an annualized revenue run rate of $1 billion by the end of this year. It has strong growth prospects in its current markets plus great opportunities to expand into new markets.

Cresco's share price is less than $10. The stock trades at only 2.1 times expected 2022 sales. I view Cresco as one of the best bargains in the cannabis industry.

DermTech

The term "game-changer" is probably overused these days. But DermTech (DMTK 8.97%) is one company that I believe truly deserves the description. 

DermTech markets genomic tests used to diagnose melanoma. The company's Pigmented Lesion Assay (PLA) product is 17 times less likely to miss a melanoma diagnosis than the current standard approach of surgical biopsy and histological analysis. And PLA is around 40% cheaper than the biopsy/histology method. 

The company plans to expand beyond melanoma into other skin cancers. That's important, considering that roughly one in five Americans will have skin cancer by age 70. DermTech thinks that its addressable market stands at around $10 billion, with much of that opportunity related to testing for ultraviolet ray damage and skin cancer risk. 

After falling close to 50% below its highs from earlier this year, DermTech's share price is now below $40. The stock should bounce back in a big way as more dermatologists learn about PLA and prescribe the test more frequently. 

SoFi Technologies

SoFi Technologies (SOFI -0.28%) is another stock that's been beaten down this year but still has great prospects. It offers a one-stop shop for digital financial services.

Although SoFi isn't profitable yet, the company has delivered four consecutive quarters of positive adjusted earnings before interest, taxes, depreciation, and amortization (EBITDA). Just as important, SoFi's membership growth is accelerating quickly, more than doubling year over year in Q2. 

SoFi continues to roll out new functionality on its app that makes obtaining loans, saving, spending, and investing easier. Its Galileo business that performs processing for other fintech platforms could even become bigger than Sofi is today

The stock costs less than $15 right now. My view is that SoFi could realistically double or more over the next five years as it transitions to profitability with its platforms.