Here's a dirt-cheap setup with high magnification. Start with an M42 Vivitar 3x Teleconverter. Add an M42 49mm reverse adapter and mount an SMC Pentax-M 50mm f1.7 in reverse on the TC. Add a bit of flash and fire away!
Here's the Eagle on the back of a $1 US Bill. For those in other parts of the world unfamiliar with the shrinking dollar... The eagle's eye is slightly smaller than 1mm.
Oh, and if you're wondering why the M42 reverse ring and TC, well that's what was in the junk drawer!
Regards,
Mike