Cost and Longevity of Botox in Lower Tummy?

I am not sure that this would accomplish anything. To the best of my knowledge, Botox is not used in the lower abdomen and I am not aware of any indications for abdominal injections.

Have you seen a physician who recommended this treatment? For what purpose? There are no thin muscles in the skin of the abdomen unlike the neck. Are you having a problem with excessive sweating in this region? If you reply with more of a precise indication or explanation of what bothers you, more appropriate answers can be given.

I cannot think of any indication in which injecting Botox into the lower tummy would be of benefit. Botox would paralyze the portion of the muscle into which it is injected - How can weakening of the lower abdominal muscles be of ANY benefit?  

I can't imagine what you would be trying to accomplish by using Botox in your lower abdomen. That said, that cost to cover a large area would be prohibitive and the results would only last 4 months. Maybe write back and describe what you are wanting to accomplish and we can discuss something more practical.