Twilio has their pricing on their website: https://www.twilio.com/pricing

I'm not sure what you mean by VIP pricing, but no one can give you a definite answer on Integration unless they know about your business model. Integration into an existing app via plugin will be far less expensive than paying a developer or team of developers to develop an app from scratch with the Twilio API integrated into the code base. It all depends on what your goal is, and if there are solutions already available for the problem you are trying to solve.