Generally speaking, transfer dye-sub printing costs £0.50 / £1.00 more per square metre depending on the type and weight of the transfer paper used. But calculating the difference between transfer and direct is a little more complicated than it sounds.
Pretreated fabrics for direct printing are 5-10% higher in cost than non-coated fabrics for transfer printing. That said, transfer paper costs about £0.60 per metre square on average, so while the fabric is slightly less expensive, the cost of transfer paper might make up for that.
Depending on the application and labour involved, a transfer system could be more economical and leave more room for growth into other markets. If you wish to offer several fabrics you may find yourself changing over these rolls several times a day, if these fabrics were available uncoated then you would lean towards a transfer system. By and large, when producing a range of different products, whether sublimating onto fabric or a ChromaLuxe metal panel, then it makes sense to go transfer because of the versatility. If a smaller company just cares about running 3 or 4 fabrics for a specific set of applications (flags and banners or backlit), they would be ideally suited to direct sublimation printing.