Deore XT brand new, cost me $55. I wonder how much money you spending on your der. 10 speed shifters work with it, it's bottom-normal..
As far as casette goes. It will cost me about $100 for 10 speed SRAM casette and chain, or about $40 for casette plus the chain. 10 speed shfters? $150ish.
Good thing about 10 speed shifters is that they up and down shift twice (and once as well). This makes for a pretty good combination. The 9 speed shifters usually upshift once and down shifts up to 3 times. (3 clicks). That means downshifting only 1 gear at at time when used with bottom-normal rear der. Other than that 10 speed shifters are a better value, say if your 9 speed broke and you have to replace it. Same money, only now you can upgrade to 10 speed later down the road.
God, I hope they don't come up with an 11 speed. I know I'd want it.