Is $1500 a fair amount to charge a patient who canceled the AM after she had any conversations about Invisalign + impressions?

I'm sorry you're in this predicament, but a cancellation fee of this size usually means that the doctor was already billed by Invisalign.  Patients that sign up for Invisalign are usually expected to make some sort of down payment before the doctor approves the case.  This down payment typically covers the lab fee and the time spent in the doctor's chair taking impressions and so on.  It's pretty uncommon for a doctor to approve an Invisalign case without receiving any payment.  I would recommend that you review your paperwork and see if you signed anything agreeing to Invisalign treatment.  Good luck with things. Sarah Thompson, DMDO'Fallon, IL

The doctor is lying to you!  There are NO lab fees until the case is officially approved which can take weeks (especially with impressions, not scans).The only thing you should pay for is the doctor's time and effort for the impression and consultation

I would be surprised if the Dr is outright trying to scam you, but clearly from your side of the story nothing had started.  It would be understandable if you had accepted treatment and weeks later had a change of heart, as this is close to the fee that the Dr is being charged for the aligners, but after 24 hours and before a ClinCheck was designed and approved there should be no fee.