The rates are usually ranging from $6000 – $10000, depending. Many clinics have installment plans whereby you can pay monthly, so I don’t think having to save huge amounts should be an issue for you.
I do know for a fact though that several clinics who see much larger quantities of Invisalign patients get a bigger discount from Invisalign themselves – they tend to be able to pass on some of these costs savings to patients, so may be able to offer you a cheaper rate. Otherwise, orthodontists tend to be a bit more expensive because they are the “braces specialists” and have formal training towards correcting misaligned teeth.
Cheers