My latest and by far favourite trick for plastic fuel tanks is to use a soldering iron. For more info on this, click on this thread and scroll down to the last post of mine - http://ttr250.activeboard.com/t50576474/cracked-fuel-tank/
The other way is to use epoxy resin (Kneed-it multi-purpose) as mentioned in the link above.
Otherwise you can keep searching eBay and this site for a second hand one to come up. They are quite rare but they come up now and again.
I would not like to quote a price on a brand new tank in Australia, the recommended retail price in the US is over $718.49 USD and bought from the cheapest online parts store that I know (www.partzilla.com) it is still $473.13 USD +postage .
Good luck!
Jarrah
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2000 TT-R250M-
Spoiler
Ported & polished, 73mm bore, Wizeco piston, US header pipe, FMF Q4, #150 main jet, #52.5 pilot jet, throttle stop screw adjusted, larger snorkel, GYT-R air filter, NGK Iridium spark plug, 14/51 gearing, NOS +