Hi Kushani,
As many people said, it will be difficult to find a prius within your budget. But you can import a decent Insight 2010. You might also be able to go for L grade or LS grade. I have few contacts who does vehicle import directly from auctions in japan, where you can select a car and give a budget limit. I don't have any contact from UK, but if you can find a UK import vehicle, it will be much better.