Hey everyone stumbled across this super useful tool today. It is speeding up my work flow with high poly meshes allot.
TL;DR of the video - Put highpoly mesh in. Low Poly mesh comes out after a few calculations.
Also worth noting that you may need to do some very very minor clean up after the retopo.
You can find the official site and the github repo below with the binary Builds and Source code.https://github.com/wjakob/instant-mesheshttp://igl.ethz.ch/projects/instant-meshes/
Did I mention that it is free?