Start with the shipping label.
Unless they and you are both in Canada, they CANNOT send you a shipping label. Foreigners do not have access to Canada Post to do this. Same problem with couriers like UPS or FedEx. They ship cross border, but the labels are specific to the country of origin.
The seller could send you the cost of return shipping, through Paypal Send Money. But he would have to feel trusting.
Unfortunately, video games are a high fraud category. Both of you may be honest as Mother Theresa and the Dalai Lama, but your high testosterone demographic is going to make this diffiucult.
So, keep it polite and low key. Don't use any angry words or phrases. Ask how he wants to handle the return shipping. It is likely that the best answer will be that you return it on your dime and he (after testing and checking serial numbers, because: high fraud category) refunds you both the original payment and your return shipping. Or part of your return shipping.
Be sure you let him know the cost of return shipping with Confirmation of Delivery from Canada to him. It can be a shock. This may be why he changed his mind about paying the return shipping.
Look at his feedback and DSRs for indications that he treats his customers fairly. Remember that he will have dealth with some unusual personalities. How did he respond to them.
If you are both polite and professional, this may work out satisfactorily.
Politely.--- Captain Malcolm Reynolds.
