Definitely include your mom in the process of finding a dog. Pets shouldn't be "surprises" or gifts; they're lifelong commitments.
You heard right about petstores - most pets come from incredibly unsanitary conditions, the "breeders" live in cages most of their lives, and the dogs sold usually have a myriad of conditions (mental and physical) for the rest of their lives. I won't get into all the nasty details but it's commonly stated that for every one puppy that lives to get to the pet store, 10 more have died at the mill where it came from. The only way to stop the mills is to stop the demand for dogs at pet stores.
Since you don't have a specific breed in mind, just some specific qualities, try looking at the rescue organizations around Calgary to find what you're looking for. Most older rescues (6 months or older) already have a fairly defined personality so you know if you're getting a hyper/calm/aloof/friendly dog. Also, most rescues organizations expose their dogs to different situations so you'll know whether they're good with kids, other dogs, cats, etc.
Here are some rescue links:
Alberta Animal Rescue Crew (where I got my guy):
http://albertaanimalrescuecrew.com/
Animal Rescue Foundation:
http://www.arf.ab.ca/
Little Mutts Rescue (probably a good one to look at since you want a smaller dog):
http://www.littlemuttsrescue.org/
Pound Rescue:
http://www.poundrescue.com/
Heaven Can Wait:
http://www.heavencanwait.ca/
Pawsitive Match (this group brings in dogs from kill shelters in Mexico - lots of little dogs available):
http://www.pawsitivematch.org/Dogs_for_Adoption.php
Then there's the Calgary Humane Society, Cochrane Humane Society, Red Deer Humane Society, etc.
Another thing to note is that most rescue organizations will take the dog back if it doesn't work out for whatever reason. AARCS adopted out a dog that later got hit by a car and the owners couldn't afford the $5000.00 vet fees and were going to put him down - they contacted AARCS and they took him back and paid his vet fees.