The cost will vary depending on factors such as size, fabric, and quality. On average, for made-to-measure blinds bought online, you can expect to pay around £50 -£60 for an average-sized window and up to £200 - £300 for a very large window. The type of blind will also affect the price; a small standard roller starts around £18, whereas a high-end Roman blind could cost upwards of £200.