If you don't intend to make frequent changes to the suspension, you don't need coilovers. Their main advantage is adjustability. If you're not on a race course, that's a rather useless feature no offense. You can get good aftermarket struts and springs which will drastically improve performance without the need for coils. Also, $1500 will get you bottom of the barrel el-cheapo coilovers. Not worth it. You can, however, get really good struts and springs for that price. Another key point is that coils don't last that long. They need frequent rebuilding. They're very expensive, impractical for a daily driver (I've seen many people who put them on, never adjust them again, and them they lock up), and need to be replaced more frequently.
2015 STi: Still Stock
04 STi, 04 WRX: SOLD