I'm going to also mention the 370z.....for that money I wouldn't be looking for a 350z I'd be making and offer on a more expensive 370z like http://www.autotrader.co.uk/classified/advert/201302215438891/sort/default/usedcars/model/370_z/make/nissan/onesearchad/used/onesearchad/nearlynew/onesearchad/new/page/1/radius/1500/postcode/ba23ny?logcode=p
I suppose it all comes down to what you think of higher mileage but that one has only done 15-17K a year...
But back on topic, if I had to choose...the roadster.