You're best bet if your looking for a straight bolt on system is a HKS turbo setup, look on Yahoo Auction Japan use google chrome as it has a japanese to english translation. If you find one then use import monster to import it. I saw one on there a couple of weeks ago for less than $300 then you're probably looking about that again to get it over here.
Chuckles is selling a turbo manifold and turbo on here for $1000
https://micra.org.uk/cmf/message/82915 , but the turbo is chinese copy.
If you check out my current turbo build
https://micra.org.uk/cmf/message/82211 ,you can see how to build a turbo manifold for under $100 (if you have welding skills) or probably $400 if you have to pay for the welds. Look on ebay people are selling T25 turbos cheap all time as they are usually upgrading from Silva, 180SX, etc.
I paid $300 for a garret T25, front mount intercooler, piping and silicon joiners off ebay.
Let me tell you right now the costs will blow out big time, you need to get a ECU probably $500 (secondhand), engineer cert ($800 - $1000), Brake upgrade ($200), Bigger injectors and fuel rail to suit ($200+), Upgraded fuel pump and Reg ($200), Turbo back Exhaust ($1000), Tuning ($700+), plus much more that I've forgotten.
I'm trying to do mine on the cheap but once completed it's still going to owe me at least $8000-$9000, thats doing majority of the conversion myself.
So as I stated above if you can get a HKS system I believe you can run it on low boost and retain the standard ECU, etc (I'm not 100% about that) but it does not have an intercooler. It won't give you crazy power but definitely a big improvement over stock, I heard they are really zippy, they run a small turbo and run on boost a lot of the time. It will be your cheapest option to turbo your Micra.
The picture is of a HKS system or similar.