Try Walmart, like everyone else in the world, eh?
Calgary's got a Costco, too; how about your city?
Aim for about 50 cents per Amp-hour. A buck per amp-hour is too high.
People who run recycling depots can be convinced to let them go at times, particularly if you come with a voltmeter and show they guys that you've found a perfectly good one. Often, it seems folks throw away good batteries. Maybe they don't realize that it's their charger that's shot, not the battery. I've picked up many that way.