We paid TONS for our new quartz countertops and they have "buffing marks" on the edges and are very dull looking (no shine). Is this normal? I have contacted the specialist that installed them and he says "that is just how quartz is"....yet in their showroom THEY WERE BEAUTIFULLY PERFECT! Does anyone have any info or a solution to this EXPENSIVE disaster?

The specialist was not a Specialist in stone, just BS. If you saw the same tops with the same edges in the showroom that looked proper and the top in your home looked wrong then the installer did not know what he or she was talking about. They should be able to re-create the same look in your home. If not they are not specialist in this area. Go back to the showroom and tell them of your concern and ask them to send someone else back to evaluate and correct the install.
Homeowners do not realize that they are much smarter then they give themselves credit for. If it does not look right, most likely its not. Some contractors feed on the doubt that owners have to get away from doing things right. Your counters are a perfect example of this.
Trust yourself on this and go back to the store and tell them to fix the problem. If you can take photos that show what your looking at do this and bring them with you. There should be no difference between the show room and the house.

We had quartz countertops installed and they show scuff marks and have very little to no shine. Is there a product on the market that would add shine to the countertops? The installer said that black quartz countertops are very hard to retain a shine. Is this true?

Any dark surfaces regardless of what the material is made of shows scuff marks quite easily. Your installer is right on with this.
Most polishing compounds used to bring up the shine are abrasive. Therefore will scratch the top if not properly done. I would suggest that you speak to the company that sold you the tops to see if they have special compounds and contractor that does this type of work.
If you attempt to do this yourself you may end up makeing the tops worse.
I know we use corn starch to polish softer tops like corian. We make a paste of it with water and the powder and use a soft rag to bring up the shine. But we never used this on dark tops so I cannot tell you if this works or not.
If you attempt to try this do this in a spot that is not out in the open in case you have no luck.

i am putting in a new counter top in one of my rental houses, what should i use....middle of the road some renters do not care..thanks chef melody

The topps you choose should complement the house and kitchen style.
If its a cheeper home (if there is such a thing) Going with formica would be the better bet as renters are going to use the top as a cutting board anyway.
If the house is upper level type then using a more advanced (expensive) material is the way to go. As the type of renters your going to bring into the home (professionals vs family of five with no real family structure if you know what I mean) will determine what you should be using.