The home depot advertised price might not include everything.

Different edge treatments have different prices. A Roman Ogee is going to be more that a simple square edge. One of the hidden costs for the fabricator is the diamond cutting tools that are constantly wearing out. I have seen fabricators use their worn out tools on customers they don't care about as much. The resulting edge is uneven, not crisp.

An undermount sink is more money to fabricate the opening than an overmount. Maybe about $200 difference.

Backsplash makes a difference- Big, small, none? with an exposed finished edge, or butted up under a cabinet so no edge treatment needed?

Slab quality makes a big difference- just like fine art: a slab with lots of movement and unusual colors might be $100 per square foot. I have seen slabs that would make Picasso cry. Other slab yards have slabs that might have the same official name but there's no depth to the color, no movement. Less money.

Of course a prefabricated slab is the cheapest. These are 26 inch wide to fit over a standard countertop. One website advertises 26" x 96" for as low as $169. These are prefabbed overseas with a double bullnose.

Does the home depot price include everything? Demo of the old countertop, sales tax, delivery, edging, backsplash, sealer, etc.? It is common for advertised prices to leave out the heavy plywood underlayment neccesary to support the granite. If the existing tile counter has plywood it is probably coming out with the demo.

Realize that labor and fabrication is normally much more money than the actual material.

I bought my granite for $400 from my ex boss- I got a real good deal because the slab had been cut and the customer changed their mind. If it hadn't been cut it probably would have been $800. If I had spent $1200 I could have got something really nice from a yard with Italian slabs.

I think the installation and fabrication was about $3000 or so. I had about 8 guys working in my house.

Are there electrical outlets in the granire backsplash? These probably need to be cut on site to ensure proper alignment. A little bit of electrical work may be needed.

Another thing to consider is waste. Most slabs cover about 40 sq feet. If you need 60 sq ft that leaves half a slab as waste. Many fabricators have partial slabs they will sell you real cheap that you can use in a bathroom.

I hope this helps, I'm trying to remember as best as I can. Maybe someone who currently works in this field can give a precise explanation of the price difference.

The Home Depot prices do not include everything.  You need to add for sink and range cut-outs, edging and backsplashes. 

I just had my kitchen done  and I hired a private contractor.  The cost for "grade A" granite installed was $63 per square foot.   Grade B is about $7.50-$10 more and Grade C is another $7.50-$10.00.  

On a side note, The Home Depot will require FULL payment in advance for granite countertops.  Yes, they guarantee the product and the work of the contractor, but paying in full upfront breaks every known rule of common sense when dealing with a contractor.   Home Depot may be cheaper,  but I'd rather maintain the control and leverage of the work being done by hiring a private contractor and withholding funds until he work is done to my satisfaction.  WIth Home Depot you'd lose that leverage and you'd be dealing with a store manager about how your seams don't line up.  

 

I have seen newspaper add's in the nedwspaper for 31.99 per SF installed, the sink cut out and edgeing was probably extra. Granite counter tops are not for the Home Depot type contractors. I have always felt the 31.99 per sf were cut off,s with butt seams.

Just had a solid mahagony front door with lead glass insert, 2 matching side lights, bevel glass transome over all three, new treated sill, S/S over sill for $4100, new lockset with matching Dead bolt in pewter. Did a lot of shopping and got the best installer in Houston and feel like it was worth the $. All material was stained before installation and hole's refinished on site. Made a $20,000 increase on the resale value, but don,t tell the appraisal district.

Thanks for all your replies; I am currently working with a contractor for my 75 sq ft counter top (Granite) (Santa Beta) install. He was recommended by a friend who is a private builder who has used him in the past. The installer named (John) is also including a double sink recessed and plywood decking. The edges will be bull nose. Also 7 in back splash except by the cook top where it will be higher. Two window sills will be replaced with granite ones. The total price for this will be $3000.00 @ 75 sq ft = $ 40.00 sq ft. I paid half up front for the materials which is two slabs. Will let you know how it comes out.