Invisalign Cost for Minor Case?

I had braces almost 10 years ago. I now have slight spacing in my front teeth. My dentist recommended Invisalign express. He quoted me $3100. I think this is a little expensive for an express case. What do you all charge for a very minor case? I was expecting around $1800-$2000. Should I still go thru with it or look for someone else? Thanks!