There are many reasons for price variations. Generally the price for countertops is figured out by square foot and many range between sixty to one hundred dollars per square foot. Costs add up quickly for large areas of counters.
Discount granite can be found for as low as thirty dollars per square foot (installation not included). Some of the factors affecting price can be color, thickness, place of origin, patterns within the granite, and mineral content.
Sometimes the granite has many pits in the surface requiring filling. Others have softer minerals which may require sealing. There are usually different levels of quality to choose from when looking for a slab of granite. What level you choose depends on what is important to you in terms of look and thickness.
The thickness of the stone affects the price. Often thinner stone slabs are cheaper. These types usually require stabilizing. Plywood is used and laminated to the bottom of the slab to strengthen the slab against breakage. Sometimes the laminating is done in the country of origin, sometimes it is done after the slabs have been shipped.
Customization to your specific counter measurements adds to the installation costs, but professional cutting and installation are definitely recommended. At the high price of the granite itself, the last thing you want to do is experiment by doing it yourself. It will be well worth the cost. Find a reputable dealer and installer who have experience.
Discuss with your dealer the way the pieces will be laid out and cut. Waste can be prevented by efficient use of space on the slab. Waste is definitely something you want to avoid when each square foot is worth a considerable amount.