If you need to invest on new markets and add them to your investment portfolio, you only need to keep one thing in mind: cost.  

According to Forbes.com there are about 1,500 ETFs or exchange-traded funds in the market today.

ETF is a marketed security that keeps tabs on indexes, baskets of assets of index funds, bonds, and commodities. ETFs trade on the stock exchange and are bought and sold all throughout the day making their pricing change constantly.  

With the ETF passively tracking an index, searching for cost will be well rewarded. That's because the competition in this $2 trillion industry has paved a way for bargains in money management.

Whether you want a portfolio of small company shares or a diversified mix of US stocks that will only cost you $46 in a period of ten years for every $10,000 invested, the list of the best ETFs will definitely steer you to the best buys.

Vanguard Total Stock Market ETF (VTI) and the Schwab US Broad Market Index will cost you $46 and $50 per decade respectively.  Schwab's US Small Cap ETF, SCHA and BlackRock's iShares Russell 2000, IWM have negative costs, and therefore, efficient making an investment in these companies healthy for your money. It's important to note as well that cost is what matters most in choosing an exchange traded fund.

What you don't need to look for are the following: performance, tracking error, and premium discount. For example, Wal-Mart recently released their 2nd quarter fiscal 2016 report and much of their investors were disappointed.

The company has been slacking on expected earnings and has been providing dull guidance despite outpacing estimated revenue. Last year, Wal-Mart's performance surpassed Zacks Consensus Estimate, but this year, it went 4 cents below estimates.

The largest allocation to Wal-Mart is consumer ETFs. Experts have advised that investors should start to monitor funds movement closely and avoid to be dragged down as the stocks go down.

On the other hand, State Street Global Advisors vice president and managing counselJoshua Weinberg has written "In the most volatile markets over the last 15 years, ETFs have continued to trade effectively."

ETFs provide transparency and liquidity making it easy for investors to spot good price. It was observed by SSGA that its trading volumes have sharply increased in September 2001 and in 2008 when investors started to put money on ETFs because of its attributes.