Raps - In that case, I would just cut them off and begin with an estimate of the price increases

... After all, if they want you to reformat your entire business to suit them, they'd damn well be ready to foot the cost for all of the customers who don't particularly want the stuff they're looking for, and who would then take their business elsewhere.
I can see it now....
SC: Yes, you people would do SO much better if you carry X, Y, and especially organic Z from that little farm up the road...
Raps: Sure thing, ma'am...Let's see...Given the increased cost and lowered availability of getting your items due to the facts that almost nobody makes them and the ones that do are tiny, the extremely limited market for these products, and the business we will lose by diverting a chunk of our operations over to the new format...Let's see. I will need to get five million in cash from you up front to cover conversion costs alone (we'll get to the serious costs later), and we will have to implement a one thousand percent markup on all of the items you requested. Oh yes, and the minimum order size just went up because of this; now the minimum is one entire 18-wheeler trailer full of goods per order, payable 100% in advance, and we'll have to eliminate giving you refunds for any reason. And, of course, the fees to refrigerate any food items you order, as these companies often do not use preservatives...Now, all we need to do is get that startup cash from you and we'll be happy to begin ^_^