Re item price...well what is going on here is that BH Photo are either:
a) listing at less than MSRP or
b) haven't updated their price on that item for a while (RPG change prices often, and no retail price list is available, everything is done on a per project quote basis) or
c) have incorrectly assigned the $971 to the 96" vs the 72"
Re shipping, it is highly likely that BH Photo will have a different shipping price. They have real time quotes based on common carrier or freight rates using UPS / Fedex which are likely some way off reality. RPG are looking up freight prices in a different system, using different carriers. RPG will charge BH Photo the same price you have been quoted, net net, BH Photo makes a loss on shipping.