I look at and buy lots of vintage guns. I hang out with a good number of people who do the same. A SBT 7E is a very uncommon gun, particularly in Canada and would have little value to anyone who wasn't a collector of a) Vintage Ithaca or b) SBT.
If you want to get a good sense of where to start with an asking price in Canada, take a look at similar guns for sale in the US. Look at Guns International and Gunbroker and every gun shop that comes up with a 7E for sale in a google search. Recognizing that the asking price is often quite different than the selling price, take the average asking price from every decent condition Ithaca SBT 7E that you find, in US dollars. (For sake of argument $1000 usd). Use that same number but now call it Canadian dollars ($1000 Cdn). Then discount that number by 20% ($800 Cdn)
That's a good starting point for thinking about what someone may pay for it in Canada. But at the end of the day, it's only worth what someone will pay and with that gun you are drawing on a very small part of the market.