EyeBrock EyeBrock:
I would tend to go with looking at our history Boots but things have changed drastically on the planet.
Building/buying advanced jets isn't a short notice thing. This isn't the Battle of Britain with Beaverbrook knocking out 500 fighters a month. It takes a long time to build an advanced combat aircraft.
My view is we should have a bit of kit that can at least defend Canada in 30 years time. 
I don't think the Super Hornet is the 30 year fighter and I'm hoping (hoping I said)
that the F35 is.
I think you're being too optimistic if you honestly believe that F-35s built in 2020 will be still be front line planes in 2040. After all, our CF-18s weren't front line planes when they were used in Kosovo in 1999, only about 15 years after we bought them. 
By that time, the F-35As and Bs (assuming manned fighters haven't been replaced by drones or made obsolete by some other technology like AA lasers or something) we're buying will likely have been supplanted by C/D models and other new planes from around the world (like China's J-20 or Japan's planned stealth fighter). 
While Canada will be given the option to update/upgrade them, given the priority all parties place on defence spending (relatively low IMHO), that may or may not happen - after all, we only just finished upgrading the CF-18s in 2010. 
And as for your assertion that it takes a long time to build advanced fighters, you're correct, but as I said, unless we have WW3, odds are the planes will be used against third rate countries - and for that we don't really need the F-35. 
If WW3 breaks out, all bets are off. However, because we've been able to avoid a major global conflict for the past 70 years, I'm inclined to think that it won't happen anytime soon. War hasn't been eradicated by any stretch of the imagination, but until someone develops a credible BMD defence, I doubt large scale conventional wars like WW1 and WW2 are a thing of the past, as the temptation to use nukes to prevent defeat (or drag down your opponent) are too high for any sane person to contemplate such a conflict.
Even if WW3 does start in the next generation, given the length of time it takes to build weapons platforms, there will probably be a massive surge and then a long lull as everyone retools their production lines to build large numbers of everything we need. 
This goes back to a discussion I had with Bart in another thread where he asserted Canada needs an aircraft carrier or two, amphibs, and all sorts of other power projection platforms. Based on our current needs and recent history, we don't, but if WW3 occurs then all bets are off and we'd probably need a lot of that stuff. 
But we can't spend our defence dollars on what we MIGHT need 20, 30, 40, or even 50 years from now, but what we need right now. Otherwise there is the potential for loads of spending for platforms that weren't ever used or even necessary - money that can be spent on things we do need now - like new destroyers, AORs, SAR planes, etc. 
The fact is that if WW3 breaks out, pretty much everyone but the US is going to be behind to proverbial eight ball to rearm themselves.
Honestly, I don't really care which plane we buy or how much it costs. 
I just want to make sure we buy the RIGHT plane, not the RIGHT NOW plane. That's why we need to hold a real competition and see which plane is the best for Canada, not just jump in and sole source a platform that may cost as much as $30 billion over 30 years.