In the old days we started small and moved up gradually ... I made a big move when I built my own house for £14,000 and sold it four years later for £40,000 (then bought a nice house for £30,000 and spent the balance on a BM)
It's a lot more difficult for your generation I'm afraid.
ETA I had to sell the E-Type for £2,000 to help pay for my self build though