$600 is a lot of money to me also but this hobby isn't cheap and I guess when your main software costs thousands then that is hobbyist level.
It's not that different to other manufacturers software in price at that level eg Moncha and arguably more powerful in some areas.
You have to remember when making comparisons with LSX pricing, that someone sitting in their University bedroom writing software can do it a whole lot cheaper than a company with premises and employees to be paid for.
Also, it's horses for courses. LSX excels at abstracts. However, you could argue that QS excels in live play and ease of use. It's all down to price and what's important to you.