Thanks for the info n2s. Where they in this exact form? If so, then that's extremely useful info. I like these pieces at art objects, but it's good to get an idea of what they sell for in their native market.
Fearn, I agree with most of your assessment, but just to be argumentative...
Your point about metal tools, wouldn't metal tools be a possibility post-contact, which, theoretically, could still place the item, again theoretically and ignoring all other factors such as the odd form, at 100 years or more?
I did turn up one 'real' example which Tim might find interesting if he hasn't seen it already. Not Polynesian, but rather African and collected in 1946.
http://anthro.amnh.org/images/full/901/901_7905.jpg