There are always ways to not pay the full payment - you can always do finance, pay a deposit and pay the full amount off when you get your build. There's a 12 month no interest period which only starts when you receive your build. No one's forcing you to make the full payment.
I reckon that'll just be restarting your wait in the new year - was reading updates and some shops don't expect to have their backorders cleared or stock to regular levels until June/July at best
The main issue I'm having with this delay is that I'm looking at my specs and being tempted to keep upgrading bits and pieces of it :P
Waiting is bad for the purse.
Some PSUs are on back order as well, and someone earlier in the thread said that getting a key for Windows had delayed his build - but really it could be anything
I know after the PCS guy posted the PSU list, a lot of people on the forum were talking about switching from the 850w to the 1000w, so that might be in short supply now
I don't know for definite, I don't work for PCS, but this is my guess :)