This depends on your preferred clinic. Most clinics would have instalment plans in place to make treatment more affordable.
For example, at i.Dental, this is the payment breakdown for Invisalign treatment:
Consultation with diagnostic records: $237.60
1st downpayment upon approval of treatment plan: $864
2nd downpayment upon issuing 1st set of aligners: $1,620
Monthly instalment: $300 – $400
Student and NSF plans are also available.