My guess is a $600 a month duplex unit is not a high-end property. I would not put granite in a moderately priced unit. I would install laminate that looks like granite from a big box store or somewhere I could get it even cheaper.
Here's a recent kitchen remodel that Eric of nononsenselandlord.com did.
http://www.nononsenselandlord.com/2015/08/july-august-2015-rental-cash-flow/#more-2892
+1 Don't put wood or stone into a rental.
The stone itself is cost prohibitive, in addition, granite, marble, travertine (both very soft stones) are quite porous and need to be sealed about once a year to prevent staining. The softer stones in addition to being porous are can also scratch quite easily. If you must have granite, I would advise to go with a stone top like Silestone or Cambria, both of which are man-made tops that have a similar look to granite, are very hard, and are not porous. Again, cost will be a big factor here.
Wood tops come with their own set of issues, again mostly surrounding maintenance. These tops need to be oiled occasionally to keep from drying out, and are subject to heavy wear and tear if the tenant cuts directly on the surface. In addition you could have a tenant decide to put a hot pan direct onto the wood top which can burn it.
Laminate is inexpensive (in terms of replacement should it need to be) and pretty durable. There are some at Home Depot in stock and as long as you can cut to the length you need, it's a good buy. If you don't have that option, you can special order to size and either install it yourself, or have it installed. They have even begun producing laminates that mimic granite color & pattern.
