There are alternative clear aligners other than Invisalign on the market. However, having patented the clear aligner technology early, Invisalign has a much more research than many of the other companies to support their current technology. Clear correct is another clear aligner system that is slightly less expensive that is widely available. With any system, you want to make sure you are getting treatment from a licensed dentist. The systems that offer "do it yourself" and "at home braces" can be very dangerous. Without properly diagnosing gum disease, decay, and other oral conditions you may have prior to starting orthodontic (braces) treatment, you can potentially worsen these conditions. Dentists are trained in so many things that are relevant to orthodontic treatment and it is not really something to be done unsupervised/on your own.