Botox (or any neuromodulator) treatment has to be customized your needs depending of your location the prices vary per unit. Other places charge per area. The best thing to do is to have a specialist analysis of you face. It is important to discuss you goals with you provider. The aging...
Botox can be a very effective option for thinning the lower face. When injected into the masseter muscles of the jaw, it can help to narrow the jaw. Takes about a month to see results and should be repeated at least twice a year. Good treatment to start with since it's easy and works!
The photo the skin band on your neck does not appear to be platysma-related. That being said, I have been treating necks with Botox for well over twenty years and have found the so-called "Nefertiti lift" to be helpful when the platysma is involved and/or the amount of loose skin is minimal, a...