I just did Ultegra 6770 bit by bit for <£130 - the shifters were £50 as they were scratched and the mechs came with an ultegra chainset in auction for £40.
I'd get the shifters first and then the mechs to suit. Then ideally look for a bundle of wiring which comes with the two junction boxes (A +B)
The 6770 route is really good - you just need:
6770 shifters
Junction Box A (SM EW67A)
Junction Box b (SM JC41) for internal
6770 mechs
External Battery and mount (SM BTR1) (Plus Charger)
and wire
You need to make sure that the wire will be long enough for your routing - mine wasn't so I just soldered on an extension to save buying new cable.