Believe us, we wish they didn't have to cost more, because we understand how frustrating the current fashion market is for plus size women. However, our plus sizes are quite different from the standard range. They are different drafts, not simply scaled-up versions of standard sizes. We've taken care to add more boning and in some cases more seams to help with fit and support. All of this comes at an additional material and labor cost.
Large manufacturers are able to absorb the cost of the extra fabrics and materials used in plus sizing across their entire size range; the XS helps pay for the 2X etc. When you're manufacturing 1,000 or 10,000 pieces, that works. However, this is simply not possible at our small scale. We've done our best to keep the pricing differences as low as possible.