I recently completed 6 months using SDC (smiledirectclub.com), an they gave me 12 trays very similar to invisalign, and the cost was $1550 (invisalign had quoted $5500, even from a dental school!). I couldn't be happier. The most annoying process was the dental impressions, which took me 3 tries to get right, but each time they sent another kit for free. If you live near one of their 'smile shops' which are everywhere but the west coast, then you can get your mouth 3d scanned for free and you can avoid the imrpession process. There are good and bad reviews of them online, but mostly the bad happens if you don't wear your aligners for the whole 2 weeks like you should. There's a good facebook support group you can find for invisible aligners that has lots of tips. I was very satisfied.