I looked into three options for buying a Prius:
1) haggling with a dealer (best saving £800);
2) importing from Eire (best saving £707, excluding going to get it!);
3) online reverse auction (best saving £1934 after auction fees).
Option 3 is obviously the one I went with in the end and will get the new car around 10th December. Can't wait.
I found the reverse auction option to be easy to use and got me the savings I wanted. Basically, dealers bid lower and lower prices against each other to sell you the car you want. Very satisfying to watch!
I guess this forum isn't to be used for advertising, so I've put more details on my own website (see my profile for a link).
There I've posted a bit more about the importing option and alot more about the reverse auction with links to the company I used to run the auction. The auction ran for a week and I've kept a blog of what happened each day (sad, i know, but someone might be interested).
Best wishes,
Adam