Yes, there are multiple flights from Toronto to Bellingham for under C$ 879. The cheapest flight booked recently is on Multiple Airlines for just C$ 844, but on average you can expect to pay C$ 847.
There are no direct flights from Toronto to Bellingham, but Cheapflights can provide you with all the information you need to find the fastest route with the fewest stops.
Expect the weather to be around 25 °C on average in July. As the temperature peaks, try to get your plans done early, as flight price and availability will have an impact on your travels. The climate in Bellingham is generally the same as in Toronto.