Thinking Ahead??

Hi Everyone!
As usual, I am sitting at work (yes, at 2:00 in the morning) blog hopping. I am coming across a ton of new things that I think are just amazing, to say the least! Every teacher's blog that I have come across so far has tons of things that I would just love to use when I get my own class.
I am still a couple of years away from graduation, but should I go ahead and start stocking up on sets and units that I could use in the future? Or would things change too much in 2-3 years? Should I start thinking about everything I want to do? I can already see my classroom in my head. My theme, decorations, everything! Should I be bouncing around on TpT and other stores like that, or just stay put for now?
I'd love some feed back from all you wonderful teachers!!!
TIA