Mina,
Thomas is correct in that until the property sells (title changes), you don't have to pay land transfer tax.
BUT... if you register a notice on the title to protect your interest in the transaction (which you definately should!), that will trigger the transfer taxes.
If the deal is good, then paying $5,000-ish for taxes might not be a problem for you, but it definately requires an analysis.
Thanks,
David.