The retail price varies wildly. If you shopped around, £4k would get you a top end machine, OK with £1k wheels rather than £2k wheels.
Take the Canyon road bike, Campag Super Record Groupset (£1,800 discounted price - RRP is more), R-SYS SLR (£1,200) wheels (bloody fantastic and light I believe), Ritchey WCS finishing kit, for the grand sum of £3,800 - bloody brilliant.
£5k-£6k is about the norm before you start getting into exotic kit. Flash wheels can be £2k, and quality framesets vary from £2k to £4k - some being a bit over priced. Take Spesh kit, some of the most R&D developed frames (like Trek) but they sit at about £2.5k for the top end SWORKS frames (excluding the Mclaren).
Other end, take the DeRosa Protos with Super Record EPS (Electronic) - no change from £12,000.