Oh yes I agree with you there CAT, however there is one big advantage to crossfire/sli spreading the cost.
If you cannot get the money together at the time then a mid rage card is often the best bet, then in 6months to a year's time you can try to pic up a 2nd one cheap with what little you've got together.
However at the same time if you can hold out, grab the high end cheap when the new series comes out, then wait for the new series to drop before going to that one.
Also being careful you can often skip series altogether.
But now we're moveing away from the original topic so I'll shut up.