What'd you pay for invisalign in London?

I'm thinking of getting Invisalign and have seen promotions around (offering $500-1000 off the total cost) - so I'm wondering, how much did you pay for Invisalign? Where did you go? How long did you need Invisalign for?

Editing to add - I’ve been in contact with a couple dentists in London and St Thomas for quotes, I was just curious what others have paid. I know it’s dependent on the individuals case.