I highly recommend N+1, but I also always recommend used. Why pay $1500 for a new Shimano 105 bike, when you can find used Ultegra bikes for around $600? And if you are handy, and do some shopping, you can do better than that.
I have about $325 into this bike (I built it up myself, all Ultegra 6501, except for the Bontrager Race wheelset). It is rare for me to buy anything new.
