Complete alfine set up of drivetrain amnd rear whell and crankset is about £250. Get a decent rear wheel, cassette, crankset and shifters for that if you can
Wrong end of the argument TJ, 9.9 out of 10 mountain bikes sold have dérailleurs specced as standard, whereas Alfine and the like are almost always after market devices, contra to your argument, you have to find the equivalent specced Alfine bike for the same money as say a Deore (where I'd put Alfine in the Shimano family) for the same money.
As for dérailleurs being rubbish from an engineering POV, OK, the parallelogram version being going nearly 70 years virtually unchanged, designed for 3 widely spaced gears, it happily copes with up to 11, in mud or whatever. Theres plenty of life left there.
Internal hub gears have their advantages, but IMO they are minimal against a well looked after traditional drive-train, and personally I'd find the additional cost of merely a different way to change gears not really worth it…