You might some helpful information here:
U.S. Citizens and Resident Aliens Abroad
My US-born wife files her US tax return herself every year and has no problems. Mind you, she only has earned income from Canada, so more complicated income situations might lead to more complicated returns.
If you just have Canadian income and it's under the Foreign Income exclusion amount, you shouldn't need to pay H&R anything.
I'd also give the IRS international office a call if I had any questions: 215-516-2000