Just powered up Leatherworking to only 470 and cost me somewhere between 10-11k. AH ran out of savage leather though so I couldn't go any further for the day. Server isn't really low pop but my side, Alliance, is a little.
I don't mind it particularly (leveling a profession as it is now), it's sort of interesting to put together different mats and try and figure out the lowest cost route to maxing it, but something like this would probably make it cheaper. At the very least it would make there be no change in the cost of leveling. You can still level it the old fashioned way, just with something like this you have the option to use current-content materials to level if they just happen to be cheaper or more plentiful at the time. But I suspect there will at least be a slight reduction in the cost to level BS with this change.