Macro Extension Tubes

I've wanted a macro lens for a while now but the one I wanted is about $800, so I found an ad on usedvictoria for a macro extension tub which is simply a tube that screws onto your camera and then you screw on any lens on top of it. It comes with 3 rings that which you can use just one, two or all three. You lose auto focus and you have to play around with it quite a bit, but it works great. Aubrey is too fast of a subject to really use it on - I'm hoping to use it for newborns to get their eyelashes, lips, fingers, toes and the swirl of hair on the top of their heads - much more still of a subject! I did manage to get one out of many tries with Aubrey though. Oh - and it only cost $25! You can buy them on ebay for under $10, but I was ok with $25.