They have human hair which is more expensive ($100-200) and synthetic hair which is cheaper (less than $100), and many of the options are "do it yourself".
That still might be too expensive, it would be for me, but it's a lot less than $1000. If you need curly or wavy, a lot of the synthetic hair these days can tolerate heat, so a curling iron would work. Or at least that's what the website says, I've never had hair extensions myself.
Also, speaking of the 1% (The kind of people who don't bat an eyelash at 1000 for a hairdo), once, while visiting my mother, we went out to dinner with someone who's job was giving people eyelash extensions. They cost $300 and have to be redone every 2 weeks. And this person able to make a living doing this because there were enough people buying.