Alas, development costs typically scale as the cube of the take-off weight. Concorde was a 100-passenger SST with trans-Atlantic range at Mach 2.2 -- it burned over 100 tonnes of fuel making the crossing and take-off weight was comparable to a wide-body, so if you want composites as well you're talking dev costs probably in the same range as the Boeing 787. As it is, Concorde cost multiple billions of pounds sterling to develop in 1960s money. Even if you shave an order of magnitude off the cost, you're still talking something that Rutan could only manage if Bill Gates or Warren Buffet were to open their wallet and bankroll him.

(Scaled Composites is no longer owned by Rutan; last I heard it was a subsidiary of Hughes.)