If it looks too good to be true, it likely is.
These waterpumps new should run in the $300+ range, so a half priced one would scare me, personally.
Alot of these off-brand pumps are built with poor quality bearings...likely by jobbers offshore. Could be a Mexican knockoff to.
I bought a rebuilt from Zims that has a 2 year warranty, and their rebuilds have the turbo style/quality bearing.