Marble is soft and rarely used in kitchen counters. Granite is harder and the most common. Quartz is the hardest, and most durable, but it's pricey.
I'm looking at remodeling right now with some basic granite counters from this brand for around $14 a square foot for the color we are interested in.
http://www.muranocollection.com/
Keep in mind that counters are a little over 2' deep so your cost per linear foot is a little more than double what your square foot costs are. So for us, a linear foot is just short of $30 per foot.
Typical granite costs for more unique/popular colors is more in the $30-$60 a square foot. This stuff is very basic and has some installation quirks that we are accomindating for.
Quartz goes for $65+ a sq/ft. Corian/Silestone is around the same price and has it's own pro's/cons. And with all of these estimates, you also have to figure in the cost of labor, delivery, sinks, backsplashes, ect.
Probably one of the better values I saw was at Lowes. Formica has a Corian alternative that came with very nice moulded in sink, bullnosed edges, and installed for around $60 a sq/foot. That was a pretty good value for including labor, sink, and delivery.