I found rennet at fromagerie Hamel at the Atwater market. Ask for Présure (french translation of rennet). It was $9.95 for 50ml bottle. They also had it in powder form at fromagerie Atwater, it was $3.99 for a tiny packet. I am making mozzarella and burrata so I needed citric acid, which I found at the drug store. I had to ask for it at the prescription counter.
I got rennet at Hamel, at Jean Talon market. It worked well. Cheese cloth was surprisingly hard to find, I ended up getting it at Provigo.
My cheese was ok--I think one of the keys is to find good whole milk. Why go through all the trouble if your source is pasteurized and kind of de-flavoured? The milk I used was d'Antan which was the best I could find.
I made a mistake though: after cutting the curd, I dumped the whole thing into a tub. All the beatiful little curds kind of got mashed. Made it a pain to pass through the cloth since there were now so many fine bits. In the end the cheese was tasty, but I'm waiting to find whole milk before I do it again. (btw, I followed this guy too: http://biology.clc.uc.edu/fankhauser/...)
Try the food co-ops or health/organic food stores for the rennet.
If that doesn't help, did you look in a supermarket? The rennet is often sold in the aisle where "Junket" powder is sold.
Below this is an LJ link to bulk food co-ops that also might lead you to a place that you could call for info, at least!
The bacterial cultures sold in shops usually are Lactobacillus and are for making yoghurt. I have never seen anything for cheese, per se.