The disability market is worth billions of pounds - and companies are coming up with ever more "disruptive" ways to break into it. Last summer was one of those rare occasions on Dragons' Den when someone pitches, nails the numbers and watches the Dragons try and outbid each other. Then in a twist, the business owner rejected an offer of £70,000 for 35% of the company. The deal collapsed and she walked away with nothing. Ellen Green from Blue Badge Company, which makes stylish accessories for disabled people, forged ahead anyway and now plans to expand internationally. "It started because my friend, who was in her 30s and very stylish, had just received her first blue badge for the car.…