Tooth extraction depends on the severity of your malocclusion. Even with invisible braces, if your case demands, extraction might have to be done.
The best invisible braces around the world is Invisalign. But yes it is expensive. Also, Orthodontists have to undergo special training to be eligible to be Invisalign Providers. For other aligners, anyone can give them out.
There are lots of other aligner companies, however the results are a little compromised.
Next Steps
Visit an Invisalign certified Orthodontist to know in detail.