Your opinion? How should I invest in these ETF's? I am 25 yrs old.
First of all, if you're 25...you don't need AGG. This is a bond index & you're way too young to need this.
Secondly, read up on what ETFs really can do. The previous blogger is correct about active management in an mutual fund usually being more advantageous. But they are wrong about the entire ETF being liquidated if a stock goes under. The entire ETF still survives. The three that you are asking about trade millions of dollars each day. See http://www.fool.com/etf/etf02.htm and decide for yourself.
Thirdly, the cheapest way to buy these would be to open a trading acct. at either E*Trade ($13) or Ameritrade ($10)...these are 2 of the biggest online brokers on the planet. If you hired a full service broker, then you would pay more (usually 1% of the trade), but get personal advice. Good luck!!
My opinion is not to form ETF portfolios. If one stock in a ETF goes into bankruptcy, you would have to sell the whole ETF to get out. On the other hand, one stock is doing very well, but it doesn't matter to a ETF because the other stocks are bringing it down. They are not like mutual funds where a manager fixes problems. You get to keep the same stocks no matter what. No one sells and replaces anything. If it goes to .10cents a share you lose.