From looking around nissan are over £250, and independent are £120-£150, but that may not include the key blade, the the remote and immobiliser fob part.
If you are looking for a regular key instead of a smart key, then it should not be too hard to find it using the same link, or simply contact the seller with your query so that they can help you better
I completely understand your view but I am a regular buyer on AliExpress, from India and my success rate in receiving the ordered products as advertised so far has been impressive.
The link to the product which I have shared with you has good reviews and someone has even mentioned that the smart key works as intended.
Personally, I'd try that if I needed a smart key for a Nissan Micra. Do go through similar ads on AliExpress and chances are identical products from a different seller may have more reviews to go through.
As I have not bought it myself, I don't know much about those things but if I needed a duplicate / spare smart key and if someone were to offer one which works at that price, I'd try it.
Other option I know is to contact Nissan for a duplicate key and they are more expensive than I want to invest on.