It is important to understand that the way technology is distributed today, most manufacturer/distributors are unwilling to allow an effective demo period in order to ensure the technology you are buying is a complete and rational solution for your needs. In fact, you can’t get a demo without signing a P.O. (Purchase Order) which means, you can become liable for payment.
This can result IF you find the product you signed up for does not work they way it needs to or if it takes longer than anticipated to build out what ever architecture is required until the solution is proven effective or otherwise.