Step 1: Find the store and their opening hours and shift your schedule to get there in time. (Most places close at 5pm or 6pm, and 8pm on the odd day. Barely open on Saturdays, and definitely closed on Sundays.)
Step 2: Browse around and price the ones that catch your eye. Find out if they have any in stock. If they need to order them from the warehouse/manufacturer, find out how long that will take and when they're placing their next order.
Step 3: If you didn't find anything that catches your eye. Go back to Step 1.
Step 4: Once you've settled on the brand and color of tile, go online and try to find other distributors of that brand, or at least, find a listing of other tile shops in the area and get their phone numbers.
Step 5: Call each of those places and ask them if they carry that line of tiles, get a quote from them if they do and see what kind of deal you can get.
Step 6: Purchase from the cheapest quote you get.
Or of course, you can just pick it up from the first place you see it at, which would be much simpler, but when tiles start costing 12 bucks a piece.. well, you really have to think about it.
Below are the two tiles we chose for our ensuite stand in shower.
Oh, and we made another trip to IKEA last Friday to order our vanity cabinets. While there, we managed to score an entire countertop (for our ensuite bathroom) for $29! Woot!