To start with you can't bring turtles(including Tortoises) into Canada without a special permit up and above CITES. Perhaps that is the permit you are referring to.
There are very few import restrictions on herps in Canada,in in general no import license is required by Canadian law, but Chelonians unfortunately is a different case.
No import permit is required by Canada for any other herp unless it was CITES appendix one.
In general the American exporter must be the one to get the CITES export permit and also to get it validated prior to the animals leaving the country and this happens during the export inspection which must happen on US soil, in the presence of USF&W and also the valid USF&W import export license holder. This is normally done at a designated port, which are at large airports.
Once they have been inspected and the CITES validated, your US exporter will be free to board them on a plane to Canada.
Letting the US supplier do all the work is the best bet, as once it's on a plane to Canada, they have done all the work, and all you need to do is pick them up at the airport, pay your PST&GST, surrender the CITES and show your turtle import permit.
Now it gets a little complicated if you want to bring them across yourself out of Buffalo but it is also possible however YOU are now the one exporting them, and you would need to be the holder of the USF&W license. AS odd as it may seem Canadians are allowed to possess this American license for the purpose of cross border transactions. But you have to apply for it, and give reason why you need it and pay for it in greenbacks
You would also pay for the inspection which you must arrange a couple days before you intend to cross.
Since you are driving you'd also need the "exception from designated port permit" This is up and above everything else. This is because there are no designated ports on the border. They only exist at large international airport centres.
From my info page on KS, here is a link to USF&W designated ports and border ports
http://international.fws.gov/animals/wildlifeport.html