To get there, it makes sense to invest in the Vanguard Total Stock Market ETF (VTI -0.04%). The exchange-traded fund (ETF) invests in roughly 3,500 U.S. stocks and charges just 0.03% annually to own it. Turning $500 a month into $1 millionRealistically, getting to that level of wealth will require a 30-year time frame. But let's start with the base-case scenario first:$500 monthly investment into the Vanguard Total Stock Market ETF. It's a mistake to think that $1 million in savings is something only reserved for the lucky or wealthy.