it is aftermarket. Nissan never did a factroy turbo. Looks fairly tidy dont knock it just because of the price it would cost around £2K to put a turbo on anycar especially if your paying for somone elses work.
no one should pay £4k for a 1.0 micra thats nearly 6 years old. turbo or not. you dont know the history of how its been treated.
£1750 is book price. i wouldnt pay £2k to have a 2nd hand turbo kit. the other mods have no value.