AnaMaria said:
If you wire transfer, you financial institution will take care of the declaration. As you mention "substantial", ask your financial institution in the US for required document. Fees are unavoidable unless you bring cash and deposit it into your US$ account in Canada. If you bring money (more than $10,000) yourself, you have to declare at customs. This is due to anti-money laundering. No tax for bringing money. But if you don't declare, you may be charged for penalty if found.
PayPal is only good for small amount of money (and I doubt they will let you transfer large amount any way).
This also applies to bonds and even a cheque!! I sent a cheque from UK to Canada with FedEx and they go via the US and my cheque for very close to $10k got held up for a week. So much for overnight.
I had to look into this as we are buying a house and are moving money from UK to Canada.
Personally I wouldn't use PayPal, they can freeze an account and funds at any time and if you're moving $xxx,xxx money through that will happen. Also the fx rate they always offer me onscreen is way out - like 2%. Over $300k say that's $6k.
Brokers. These are oanda etc. When I got quotes they were 2% off spot and that was picking say 7 points throughout a day over a week. I even spoke to one of their traders about the rates and they couldn't improve them. The fx rates they have on their website are different to the fx rates available to trade.
Banks. Some banks have bad rates, some better. Some have fees. Because a number of brokers have gone bust and my bank offered better rates AND there was better safety for my funds, this is how I have been transferring in multiple transactions to even out the fx rate.
I found the best for me was to look at all avenues and work out what you would ultimately end up in your bank account, what was the risk, how long was the money gone for, and then make a decision. I have a big spreadsheet and monitor trends etc so I can ring up and get the transfer done.
Use xe.com or fx street for live rates.