Ultimately what people want to feed their cats is up to them, but the "I know cats who lived long, healthy lives on grocery store brand cat food, so it must be okay" line of logic drives me crazy. Anecdotal evidence doesn't mean anything - my grandfather, for example, is an alcoholic who smokes...
I see you're in Toronto as well - I would expect to pay around $60 for an exam, more if additional care (medication, testing) is needed. Spaying at a veterinary clinic is around $300, but if you call the Toronto Animal Services low cost spay/neuter clinic spaying will only cost $80, I believe...
I have an Amarkat, and would definitely recommend them - they're cheaper than you'll find at a pet supply place, though still a bit pricey, but all of my kitties just adore ours, so I think it was mroe than worth it.