I am the representative of insubuy.com and we are replying to this question because the original poster has questions about our company.
You should always purchase from a broker such as insubuy.com because there are many advantages such as expert advice in plan selection, side by side comparison and after sale support, longer service hours etc. Please read http://www.insubuy.com/why-purchase-from-insubuy/our webpage on the topic for further details.
And of course, there is no disadvantage in purchasing from a knowledgeable broker such as insubuy.com as the prices are the same as anywhere else.
Regarding discounts, they are illegal. Any licensed agent who passes the exam before getting license has to study that. The state laws in the US explicitly prohibit that. You can definitely confirm that by calling your state's Department of Insurance.