take a look at the federal 595 RS-R tyres, they are fairly cheap for a decent road legal semi slick.
otherwise check out http://www.tirerack.com/ they deliver internationally, though expect ~$200 for freight and a $30 international money transfer charge when you pay for them, friend just got some 265 17's Michelin Pilot Sport PS2 tyres for just over $800 delivered, the cheapest price he could find one tyre for in australia was just under the price for 2 from the USA even with delivery etc.