Think you have added a zero to the price of a reversing ring, it should be about £12, not £120! And my old fifty millimitre M42 mount cost me £20 IIRC so thirty odd squid.

Actually thats not too bad.  I was looking at some Sigma reversing ring that was £120 - so maybe a pro type of sorts?  I think I will pick one up and give it a go.  I want to do a comparison of the following

Sigma 70-300 APO DG (in Macro)
50mm with reversing ring
50mm with extension tubes
50mm with close up filter set

Any thoughts as to which would be best?  I am pleased with the macro on the sigma zoom/macro lens, but as its not a dedicated macro lens it does not get in close enough.  Just do not have £250 for a dedicated macro so weighing up alternatives given I have the 70-300 and a 50mm