I live in Toronto. last year I drove down to Buffalo to open a US bank account, which works like a dream. Possibly the best thing I have done in 5 years of being on eBay.
Now I can transfer USD online from PayPal into my US bank account for free (there is no fee to do this into US bank accounts) and use my MasterCard debit card for any purchases here or in the US, or withdraw $$$ from any Canadian bank machine. I also got cheques that I can use to draw on the funds. The exchange rate they offer is the best I found.
EBay also gives me a PowerSeller discount for using my US bank account to pay for fees.
Another thing, US Banks are much more aggressive, their customer service has been A1 and they have given me overdraft protection and even a line of credit. They go MILES beyond what any Canadian bank would.
You also need to apply for the PayPal debit card (they offer 1.5% cash back when you use it) and the merchant rate (2.2% fees instead of 2.9%) which will also save you lots of $$$...
These are GOOD tips that took me years to figure out, enjoy!