Just depends on what you want to do, I bought a $2000 bike and dropped a couple hundred on it right away. The bike didn't "need it", but I wanted a little better performance, some people understand and others think I'm throwing away money. Do what you want to do, because there really is no clear answer to your question.

I don't think there are many bikes out there that are set up perfectly from the manufacturer for any individual. Most bikes no matter the cost will probably have something the rider would like to change, for example: a bike seat, gearing, or better brakes