A $10 share isn't cheap and a $500 share isn't expensive. What matters is the price of the entire company: share price multiplied by the number of shares.
That figure is market capitalisation. It's how you tell that a $30 stock can be worth more than a $900 one.
Cap also tells you roughly what kind of ride to expect. Mega-caps move slowly and rarely disappear; small caps move violently in both directions.