Focus Rack Advice Please

I want to do focus stacking of flowers using D800 and 105 micro VR.I waant a rack but have never seen one and not available locally. Considering the Novoflex Castel-L $330 at B.H. I have no idea if this is a good choice. The racks seem to be very light for a heavy camera/lens. What would you buy for less than $400 ? Cheers Doug