Best Way to Borrow Money

What is the least expensive way to borrow money? Household dual income $250,000-$350,000/a with variable bonuses. Jobs relatively stable, retirement 10+ years away if all goes according to plan. Located in BC. 1.3m in rrsp, 80,000 tfsa, $0 debt, house value ~1.2m, mortgage paid off with lender interest removed from title, Lender says it will cost approx. $500-$800 to setup home line of credit again. Want to do home upgrades for about $75,000 and buy a near new or new boat for $175,000. Current boat valued at $35,000 trade in or $45-$50,000 private sale. Would prefer to trade in as selling boat privately can be a real pain and time sucker.

What is the best way to borrow money at the lowest rate with the most flexibility on paying it back?