I wasn't seriously expecting to get that 1.7x - the seller set an insane reserve, as it turned out far more than I was prepared to pay. No harm in trying though
(and no, afaik it doesn't support SDM)
On the subject of customs, remember that you have a $700 allowance (in stuff like electronics you can bring in for yourself), under which customs do not collect duty.
Things like jewellery, clothing, etc have no GST applied, provided the items are for your own personal use. Also, it is $700 PER PERSON, and cannot be combined.
As I said before, when I bought my K100 Super (in the UK) I got through customs here without paying GST - I declared it, but I declared the value in pounds (it was about $900 I think) and whether they decided to cut me a break or just didn't want to do the paperwork, they let me through without paying.
If you're in doubt about what you can, and cannot do, ask a customs officer when you're leaving - they're actually pretty friendly when you aren't breaking the law. I had a nice chat about cameras with the officer while getting my certificate of export the last time I took a trip.