I think you should buy the PSU though, it is a really good price since it is on sale at the moment where you are buying it from. It is usually more expensive than the HX (still Gold and modular), but at eBuyer it is cheaper at the moment. I dont think they will change from here till Haswell. I would wait to buy everything else though. Prices may decrease and such, plus the RAM may need an update to support Haswell. Finally, there is a new rumor saying nVidia will launch their 700 series at Computex 13'.
Well I think I'll wait then, it's always nice when you do a new build and you have the the most latest technology you can cram in, I will buy the PSU though like you suggested if nVidia do that then their entire range should see a price drop that will be worth looking into