I know they have to do the trades at the local brokerage when you're dealing with Canadian warrants, but we haven't had problems buying Canadian stocks online at Scottrade.
A "broker ssisted" trade, which is the type of trade you've referred to, is listed at $27. That's an outrageous amount for a simple order, and it is why we trade on Scottrade only when it is convenient.
They shouldn't be overcharging you any more than that in any case. Call the headquarters in St.Louis to verify rates for specific orders.