I think the price point Mongo suggested is probably a practical starting point, although mine has been a little lower depending on the goods.

For example, I've found the price differential between Aus and OS is pretty low on some third party lenses like Tamron or Sigma (if you shop around) whereas Nikon you pay a premium, particularly on accessories. For this reason, I purchased my Tamron 90mm Macro locally despite the asking price being about $600 because there was only a marginal difference. I did however buy my light meter and my nikon 1.4x converter overseas as I found locally it was nearly double the price and under the $1K mark had no GST so I could land it at about $350 vs the $650 they were asking at the time. I figured if things went pair shaped, I could buy another without making a loss, and realistically, teleconverters are less prone to issues because you don't use them all the time. I think I bought my SB600 OS, although the SB700 I got locally because I negotiated a bulk discount with a couple of other items. Again, flashes aren't normally problematic.