Orthodontist cost - is $6000 very high or about right for adults?

I had my consultation at an orthodontist this past week, and the plan is to put regular braces on the bottom teeth, and maybe invisalign or maybe regular braces on the top teeth. It is not bad like a lot of spacing or torqued teeth, just crowded. And I am an adult. They told me cost for adult is between $6000-$7000 - it would come out around $6300. I was prepared to hear maybe $4000, but was shocked at this price. Anybody have experience with same situation and can advise me about this price? Thanks! :)