hmm bought an expensive dslr and the nor cheap objective and built a ring flash for it? or its just a illuminator for macro?
You should see some DIY macro setups people have come up with, if you're not seriously into it then there is no reason to spend more than $100 on a full macro setup, aside from the camera body.
Reversing rings that let you mount lenses backwards can be had for under $5, this gives you the flat field you need for macro along with some magnification. Get a set of cheap extension tubes for $20 or if you want more flexibility a bellows for around $50. If you don't have a lens capable of controlling the aperture without being mounted to the camera normally, you'll need to pick up something, a $10-20 manual prime from the 70s will work fine and the mount doesn't matter since you're using the filter threads. Add in a $20 DIY ring light or maybe an old manual flash with a DIY softbox on it and you've got a full macro setup capable of amazing shots.
Photography is all about experimentation, would you rather spend $100 on a full setup or $400+ on a dedicated macro lens, $200+ on a real ring light and a few other miscellaneous things just to experiment with macro?
Adult male Paraphidippus aurantius Jumping Spider (With Cannibalism Video!) by
Thomas Shahan, on Flickr
Eye Arrangement of a Hogna Wolf Spider by
Thomas Shahan, on Flickr
This guy uses a similar setup to what I described, you could replicate his ENTIRE rig for $500, including buying the camera body, since he just used an old K200D.