how to achieve great macro magnification

After long reading in the internet I managed to achieve quite impressive macro magnifications. There are many products out there e.g macro lenses, extensions tubes , macro filters etc...
I wanted some way to achieve macro magnifications more than 2:1 in a cheap way. I already had a nikon 70-300G and a nikon 50 1.8 . So I read somewhere(I think it was dpreview) that we can rotate the 50 1.8 and position it in front of other lenses to achieve macro results. What I thougt was to use the 50 mm with my longest focal length whitch was the 70-300. I tried it with the help of a reverse coupling ring and got extreme magnifications. If I remember correct in the following photo I achieved a macro of 6:1 and in some other examples I even managed 8:1. The only problem is the very narrow depth of field.
The following is a photo of a grain of pepper.

Nikon D80, Nikon 70-300,Nikon 50 1.8 , ISO 400, f14, 1/200 sec