Auto Express do an "Aim to pay price" for each new car. They say its what buyers are actually paying for their UK cars across the country and say "if your dealer wont meet our aim to pay price, walk away"
Their aim to pay for a 172 from a UK dealer is £13441 and £12097 for a Cup. Both of those are about a grand off list.
You can obviously get a 172 cheaper from a Car Supermarket, but expect zero service from most, coupled with lies about when it will turn up in a lot of cases. However it is still the same car, so you dont need to worry about spec - there is only 1 type made from the factory and the only differences are on retro fit items that are fitted by UK dealers - i.e. Cat 1 alarm. Warranty is the same 3 year one, provided it was sourced (by the car supermarket) from within the EU, so its worth getting proof of where it came from before buying. A 3 year warranty is worth quite a bit of money, so getting one from outside the EU could be false economy as you only get 1 year.
The 2 common places that sell 172s are Motorpoint and Trade Sales, and Ive heard bad stories about both with regard to their customer service. I got mine from a smaller supermarket, simply because Motorpoint didnt have any blue or black ones in stock, and Trade Sales couldnt give a firm date.
As it turned out, my supplier lied through their teeth about their stock status just to get my to order through them. I was told it was sitting there ready to be registered when they got my money. I didnt actually get it until 3 weeks later - not bad compared to some peoples waiting times, but when you expected it at the end of the week you ordered (like you were guaranteed), its not so great. They lied throughout the whole process and I found out that it hadnt actually arrived in the UK until a couple of days before I eventually got it! When I chased them once to register it, they told me they had and I asked for the registration number. Would you believe they made one up to shut me up!! I got it put on my insurance and everything, and then when it arrived, the reg no was totally different.
I saved about £3000 in the end, but the hassle factor was pretty high. If a dealer had offered one for £13000 - maybe even £13500, Id have gone with a UK model. I did ask a dealer if theyd give me a years free insurance instead of a further discount, but they said it was impossible. Not sure if they just didnt want to, or really couldnt for that sort of car!