I have an OLympus EPL-1 which was quite cheap at the time and I remember when I first got it, some plain tube extension tubes along with a MFT to M42 adaptor i was able to get a very tight framing with my legacy 50mm lens.
That was with my Panasonic G3 so I repeated the exercise with the Oly.
Those are millimetre markings on my ruler. The camera was not quite square to the ruller hence the '10' is reaasonably sharp but the markings are Out of Focus
I think the netting which some oranges came in is a reasonable simulation of a coral formation though very hard to focus on so much easier with my Panasonic and its 10x zoom 1/10 handheld at 150mm angle of view. So the subject matter in one of my pyrex bowls with about an inch of water..
I started with the full set of extension rings 65mm but results very poor
So I took off the two smaller rings and just used the single long one 43mm
The message I get from all this is that the suggested rig is not the answer and to stick with The AF of my GH2 would be my choice though possibly more expensive than the $1000 suggested as an upper limit.
That you cannot beat AF and OIS for good images properly taken with a reasonably modern camera.
I will see what I get with a CU lens added to the zoom on the GH2 when I take it. [ My habits from bridge cameras dies hard ]
Typical of CU lens it is soft arong the edges but if the subject you want only occupies the centre then what does that matter Two dioptre at about 175 on the zoom.
Next adding a 16mm extension tube to the rig and able to use all 280mm zoom ... just to show I am learning and trying new things
So that is it, hope of interest so at least one person