How to tell if A 3d printing kit has a replaceable nozzle
Prusa has a replacable nozzle. Usually all printer does have an replacable nozzle. Since this is a part of a printer which could get jammed during a printer life. 

As written here: https://www.prusaprinters.org/prusa-i3-is-now-1-75-mm/ The Prusa i3 uses an E3D Hotend. This Hotend has many diffenez nozzles. You can search on E**ay for E3D V6 0.1mm nozzle and you will find a lot of offers.