I live in Edmonton -- there are large numbers of apartment houses in the many blocks to the North and North-East of Grant MacEwan. Many of these are cheaper than $900/month for a small apartment. However, to find a place, you just have to walk around or drive around and look to see which ones have vacancies (most of them are 3-4 stories tall, not large). Since there are so many, it might be easier to look in the area around schools that your children might attend (getting kids to school is simpler when they can walk). Victoria High School is a good possibility, it is on 101st street, my wife knew some immigrants who lived fairly close to it for, I think, around $700 a month.
All of the schools around here will be a little 'inner city' -- some are good, and some are bad. Victoria HS is an arts school, I think it has a good reputation in that line.
Try to arrive in Edmonton on Sunday night -- a hotel room costs at least 100 dollars a night, so you want to minimize how long you will be in one. On your first day, open a bank account, get your student card, and perhaps a SIN number. In the evening, walk around the neighbourhood I described and write down the phone numbers of every place that has vacancies. Call them that night. Look on Craigslist as well. If you can find a private place to rent for a single month, that will let you look more slowly, as well as avoiding the upsetting problem of finding a good place to stay that will be ready in two weeks.
The next day -- hopefully -- you can look at some places. They will run a credit check that might take a couple of days. If you don't have a bank account, there is no hope of renting. Don't rent the very first place that accepts you -- your aim is to be out of the hotel by Friday. Remember, you want to be within walking distance of either MacE or your kids' school, ideally both. Driving is no fun in winter, and parking is always a nuisance in Edmonton. There is a large grocery store on Jasper Avenue that is close to Grant MacEwan, and another on 104th Avenue, so if you can walk to school, you can also walk to buy groceries.
hope this helps! Let me know if you have any other questions, or are curious about a specific area.
