I'm just starting to become familiar with this discipline and I learned pretty quickly that I'll need a focusing rail to get desired results. If you feel inclined I like your views on the best bang for the buck for a focusing rail.
Depends on how often you plan to use it. Casual use? Chinese knockoff Leofoto has a relatively cheap copy of the RRS rail. One thing about the Leofoto is the rotating clamp that allows linear (focus stacks) or lateral (wide angle shifting) uses.
Other options are Olympus (and others) bodies that are capable of focus stacks in-camera that produce great results if the subject is stationary. IF light is good, stop down. F9 at a few inches is still going to have a thin depth of field.
Or, simply put the camera on a mount and take multiple shots of the subject adjusting focus each shot, then use software to align and blend the images. If your lens isn't square to the subject, leave room to compensate for focus breathing and the final crop. I typically use this technique.
