Theres usually a few on Pistonheads for sale. There is a considerable jump in price from the Version 4 to Version 5 and 6. So decide whether you want to keep it standard or modify it. No point payin the extra for the newer car if your going to replace parts later.
If you import one yourself you will need to get a model report and a SVA test for any car under 10 years old. There are big savings to be made in getting a car from Japan but costs start mounting up once you have to Register, MOT, model report and SVA the car you choose. Have a look tho, theres lots of good cars in the auctions.
www.autoadvan.co.uk
Best of luck in your hunt [Y]