Stephen,
Not even more bread and water for Sarah and James.
Not to sure if this is any help.
Used D2Hs - same body and control layout as the X. Grays currently £1649 so that will definately be put away in adverse conditions.
Used D200 - great spec, but a used one as you say will probably be put away when you need it.
New D80 - probably better with a used D200. Same problem though if it comes in around £700 - 800.
Used D100 or D70s. Your familiarity with your fathers D70 would be in its favour over the D100 in your case also compatability with your flash SB800 & SB600. If all of my lenses were f2.8 then it would have been very hard to justify a move to the X. Bonus of the D100 is that it accepts the good old cable release and the battery life is superb, Stevie still has hers. Just got Grays up and a D70 mint- £395 and D100 mint- £435.
After all that and in view of flash compatabilty D70s or used D200.
Don