If you are aiming for the M9 and only the M9 then I think it might be worth it to wait until the M10 comes out as M9 prices should go down a bit. There might also be a few second hand M9s in the market by the time that happens but given Leica's production speed it should take quite a long time for that to happen. I usually buy older digital bodies when the next generation comes out.
However, I found out that when I finally get what I want I forget the cost and just dwell on the joy of ownership. I remember when I dropped a grand on my first Leica - a mint Leica M2 with lens last march. It cost a lot for me (relative to my income - I'm a poor student) but using it every weekend for the next months gave me an intrinsic ROI. I guess what I'm trying to say here is that if it will make you happy then go for it.