Besides funding a mortgage with a US lender, you may have the option to draw upon the equity of your Canadian property that would enable you to pay cash for the Point Roberts property. RBC bank for example a home equity program where you can apportion principle balances for different properties under a tiered mortgage plan. As a "Realtor without Borders", I am licensed in B.C. and Washington State and offer clients additional guidance on who to talk with regarding cross border tax considerations, escrow procedures, and other US practices that are helpful to Canadian buyers.
I'd be happy to help you with buying in Point Roberts where I can meet you in Vancouver and represent you in Point Roberts!
All the best,
Macdonald Realty/Windermere R.E.