After dumping too much money into stuff I didn't need, 90% of my riding is on bombproof aluminum wheels. When I race, I use 50mm carbon tubulars, not because they're that much faster (for me), but because I think they're sexy and I'm old enough to admit I'm vain. If I didn't buy them when I was throwing around money, I probably wouldn't own them today. Much like the dedicated TT bike, disc wheel, and all of the other stuff I use a handful of times a year, although these things actually do have an effect on my performance. Bang-for-the-buck, even allowing for the fact that none of it was retail, I'm shooting blanks.
1 thing made me faster:
A structured training plan (especially in the off-season). Instead of getting fatter, I get lighter and stronger. I hired a coach, because my attention to detail and follow-through is weak in this regard unless I think someone is looking over my shoulder. Again, I'm old enough to admit it. I first trained by perceived exertion, then by heartrate, then by power. Each has taught me a lot about my capabilities and potential, but only when put in proper context. Otherwise, you just end up with an expensive eWang. A power meter doesn't make you faster. It's an indicator, not a generator. Without the training plans and analysis tools, it only adds weight to the bike.
Do a few races. Get dropped. Make stupid attacks. Play with pack positioning. Figure out where you are weak and work on that. Don't waste a lot of money for incremental gains when there's still a whole lot of low-hanging fruit out there. You have years to waste money- don't be like me and rush it.