Hi @Cory S.
I'm not an expert but I do live in Edmonton and I have a few thoughts you might want to consider.
First, I think it's too early to panic about the economy. Oil prices have hit the skids and oil companies are laying people off, which as you point out, can have ramifications for those in support industries like construction. But if you believe most local economists (and I'm not suggesting you should) the downturn we're starting to see is likely to be less severe than 2008-09 and not last as long. And so far, while there is a glut of real estate on the local market right now and it's not moving as quickly as it was, I understand prices have remained steady. So far.
Second, while it is true some workers will head home to Ontario or Newfoundland as they lose jobs, current provincial government forecasts still anticipate continued population growth, in the order of something like 80,000 people -- which is decent for a province of 4 million. So even if real estate prices stagnate or even decline, I think there will continue to be decent demand for good rentals. At least I hope so, because I have one.
Third, don't forget that in addition to the $500-600 you say you'd be saving on rent, you'll also be pocketing the equity you'd be building in your property -- equity that the renters in the basement will be helping you build. If the market does drop in the short term, history in Edmonton suggests it will recover soon enough, and grow. And even if that takes longer than usual, you're still building equity as you pay off a mortgage that's about as cheap as you'll ever get.
Fourth, I don't think the borrowing rates should concern you. They're super low right now -- you can lock in for something like 2 1/2 per cent for 5 years -- and are unlikely to go up anytime soon, as the Bank of Canada only just drop its rates last month. Of course, anything can happen in the longer term.
All in all, I don't think you should be afraid, especially since this would also be your primary residence, thus saving you from throwing rent money away. If you're really unsure, there's no harm waiting a few months to see what happens with the market and/or your job. This house that you're considering sounds like a good buy, depending on where in Edmonton it is, but there will be others in the months ahead.
Whatever you decide, best of luck, and welcome to BP.