Many people assume that you have to have a lot of money if you want to invest in the stock market. That's far from the case, though. Many brokerages allow you to open an account with just $100 or less, and many well-regarded brokerages are charging $0 per trade, too. Some brokerages even permit you to buy fractions of shares -- which can get you into, say, a $200 stock with just $50.

So if you have, say, $3,000 or $1,000 or even $300 to invest, that's a very reasonable sum -- as long as you don't expect to need that money for at least five, if not 10, years. The stock market can be volatile, after all, and you don't want to have to sell when your holdings are temporarily down.

Here, then, are three companies to consider for berths in your long-term portfolio.

1. Etsy

You probably know of Etsy (ETSY 2.44%), which is a premier online marketplace for handmade and vintage items, among other things. It may be bigger than you realize, though, as it has grown to encompass more than seven million sellers and more than 90 million buyers, with a market value recently approaching $18 billion. The company notes that it's the seventh most downloaded shopping app in the iOS App Store and that it features more than 120 million items for sale.

Etsy got a boost from the pandemic, as millions of people who were isolating at home became more active online shoppers -- and it didn't hurt that among Etsy's offerings were lots of handmade masks. Few people are isolating at home these days, but Etsy is continuing to grow, with its third quarter results featuring revenue up 11.7%. The company's bottom line was red, though, as it took a $1 billion write-down related to its previous purchases of specialty retailers Depop and Elo7.

Etsy's stock looks attractively priced at recent levels, with a price-to-sales ratio of 7, well below its five-year average of 11, and a forward-looking price-to-earnings (P/E) ratio of 38, below its five-year average of 63.

2. Berkshire Hathaway

Berkshire Hathaway (BRK.A -1.05%) (BRK.B -0.83%) may not be a household name, but it should be. It's one of America's biggest businesses, helmed by Warren Buffett. The company is a conglomerate, with a wide variety of wholly owned businesses under its roof -- such as GEICO, Benjamin Moore, See's Candies, Fruit of the Loom, Clayton Homes, the McLane trucking company, and the entire BNSF railroad. Berkshire Hathaway is also a major stockholder in some rather big companies. For instance, it owns roughly 20% of American Express, 8.4% of Chevron, more than 9% of Coca-Cola, 12.6% of Bank of America, and about 5.6% of Apple.

Why would you want to own stock in Berkshire Hathaway? Well, the company is built to last and is conservatively run. It's very diversified, too, with major operations in insurance, transportation, utilities, and much more -- and many of those businesses are rather defensive, likely to do well in a recession as well as in good times. It's appealingly priced these days, too -- with a recent forward-looking P/E ratio of 22, well below the five-year average of 26.

3. Boston Beer Company

The Boston Beer Company (SAM -2.10%) is an often underappreciated giant in the beer aisle, with a recent market value approaching $5 billion. Launched in 1984 to craft-brew Samuel Adams beer, it now encompasses Truly Hard Seltzer, Twisted Tea, Angry Orchard Hard Cider, Dogfish Head Brewery, Hard Mountain Dew, and Sauza Agave Cocktails, among other brands.

In the company's fourth quarter, revenue was up 27% year over year, though profit margins took a hit due in part to supply chain issues. While many companies carry a lot of debt, Boston Beer's balance sheet is debt-free, and its cash position nearly tripled between 2021 and 2022.

Boston Beer's stock appears attractively priced, with a recent price-to-sales ratio of 2.4, well below the five-year average of 4.1. The stock has lost about two-thirds of its value since a high in April of 2021, but its future seems promising. Long-term investors should take a closer look at this brewer.

These are just three of many promising stocks out there. A little hunting, in Motley Fool articles or elsewhere, will likely turn up many more. See which ones are most compelling to you, and park your dollars in the companies in which you have the most confidence.