First check the service record, make sure its been serviced regularly so there is a good chance the timing chain has not stretched.
Check the tyres have a decent amount of depth left as tyres are not a regular size (185/50 r16), so the prices for 1 tyre vary from £90 -£110 at the moment, you maybe able to get them cheaper if you do not go for the big names (Kumho KH11 ecstas are not too bad alternative about £65 each). Make sure the alloys are not damaged as they are expensive to replace or fix.
Check the rear door lock does not make a noise (like its loose) whilst driving common problem with K12's, also the doors sometimes have problems opening because of the linkages.
I had a problem with the 6CD changer in the dash with mine, would stay on all the time and drain the battery, was told by Nissan its a common problem, so check that it all works ok and make sure you have a good warranty.
Road Tax is quite expensive with the 1.4 Sport+, I pay £155 for the year
MPG is not too bad I get around 45 and I drive fast, keeps up with or beats most cars to about 80mph then it runs out of puff, but surprises some people that they are getting beat by a Micra. If you want performance go for a 160SR, the 1.6 engine makes a great deal of difference.
Check no strange noises coming from steering as its electronic and can be costly to fix.
Check all windows wind up and down, most Micra's have window issues sticking coming off of rails etc, electric windows are slow on all K12's so dont worry too much about that.
