Actually there is quite a difference between what Toronto can offer and what other teams can offer due to some peculiarities of NBA contract rules (Bird rights etc.). I don't wanna get into the specifics of it, but Toronto can offer Bosh
a longer contract with higher % increases in salary each year than any other team, and were Bosh
to leave Toronto after his max 2010 contract, he would be eligible for more money since your max is a % of what you made in the previous year.
I didn't do the calculations myself, but over the span of 7 years Bosh
could make $30-40 million more in Toronto than any in any other city. I'm not saying he won't be leaving, I'm just saying it won't for the reason that Toronto is unable to match other contract offers (unless they deem him not worth max