I've been out of the marble and granite scene for about 20 now, so I'm not sure where the pricing is these days. Most marble shops install these days, so go with someone who is experienced in installation. Edge detail will have an effect on pricing.
Marble: I wouldn't recommend a marble. You have to realize that when you get a polished surface on stone, that is the raw stone that's been mechanically polished with abrasives going finer until the surface is shinny. There's nothing on there to make it shinny, it's just raw stone brought up to a shine. Marble is generally softer, other than green marbles that are the hardest of most marbles. Marble is calcium carbonate which is alkaline and generally has a high absorption rate and porosity. When acidic liquids get spilled on the marble, it eats into the surface and dulls the polished finish. A marble polish can help protect it from this occurring kind of like waxing your car but it won't last. Marble polish does not polish marble, it only helps protect it. About 20 years ago, there was a fad where everyone wanted white marble like what the Italians have used for the past 5000 years. The Italians generally would use White Carrara with a dull finish and would use olive oil on it. They were basically staining it with oil to help protect it from other stains like tomato. So these customers were ordering White Carrara with a honed (dull) finish and oiling it. I can imagine that these counter tops got a bit schitty after a while.
Quartzite: Quartzite tends to be very hard, but may have an increased porosity and absorption rate. Quartzite is made up of quartz crystals which are very hard. We redid out kitchen about 2 years ago and my wife picked out a quartzite. Not having much experience with it, I consulted my brother-in-law who is in the business. He said that quartzite is the hot seller right now. The shop that fabricated it sealed it in the shop and the contractor sealed it after install. Typically a silicone impregnating sealer is used. It doesn't lay on top, it get absorbed into the stone to seal off the pours. So far, so good except one slightly dull spot where my daughter cut up a lemon and left it there overnight.
Granite: Granite is hard as a rock. Different geological make up from marble and quartzite. Not sure because I'm not a geologist, but it's the hardest of these options. It's so hard that in order to polish it, you need to go all of the way up to 3500 grit. I had granite for 20 years and it still looked new. Possibly the highest price, but not necessarily. Quartzite and granite are probably comparable in price.
Silestone or Granerex: FC mentioned Silestone. These are man made products from crushed up granite or something and then reformed into a slab. Not sure about this stuff because I never dealt with it. From what I hear, it's very durable and less expensive. Same basic care as natural stone.
Concrete: One of my customers, who is a stone mason, did concrete in his kitchen. He likes it and if you do it yourself it's cheap. He even imbedded coins and shells into his. Kind of unique. Other than that, I don't know much about it other than you buy a kit and you can color it however you want.
Hope this helps.
