All of us are different so we'd all have different recommendations (ain't life grand?
) but my personal recommendation is to get at least a 1k and a 5k stone. Really a 4k to 6k stone would be fine for the higher grit stone. The 1k stone will sharpen the knife well and the 5k will refine the teeth from the 1k even more to make for a nice edge on a kitchen knife. I would also recommend a strop of some kind to use after sharpening for further refinement and for use instead of a knife steel or ceramic rod. The strop will do the same thing for the harder steel that a regular steel does for softer knives. Then you can add other stones as you learn more about sharpening and what you want your edges to be like.
This set seems to be a popular one for folks around here: http://www.chefknivestogo.com/4pcshstset.html
It's a two piece set with a 1k and a 6k stone as well as a couple of accouterments to assist with sharpening.
Or you could go the full monty and get this set: http://www.chefknivestogo.com/knshcoset.html
It has 3 stones, a 500, a 1.2k, and a 5k, as well as a flattening plate (which will be something you want), a stone holder, a sharpie (helpful for learning to sharpen), and the felt block and loupe the other set has. This set it also pretty much ready to have a strop added as well. The 3" x 8" strops that fit the flattening plate and compounds/sprays are found here: http://www.chefknivestogo.com/strops.html
At the very least you'll want the stones (1k and 5k) first and you can just use the 5k for touch ups if you like. The other stuff can be added on later.
For other knives, I dunno that any will necessarily be any better than the Kohetsu for the price or comparable for less.
You might look at the Goko 240mm: http://www.chefknivestogo.com/gokogyuto240mm.html
It's a handmade gyuto with white #1 steel which will take a blazing sharp edge but won't keep it as long as the Kohetsu will. That isn't really an issue for a home user generally though. White #1 is about the easiest steel to sharpen and takes what is probably the finest edge of any steel. Plus Gokos are sharp out of the box.
Another white #1 knife I feel is worth consideration is the Yamashin 240mm: http://www.chefknivestogo.com/yawh1gy24.html
It will not have the same cutting performance out of the box as the Kohetsu or Goko or the same level of fit and finish, but with some work on the stones it can really come to life. Just know that it will take some work to thin and sharpen to get it to where it needs to be. Think of it more as a project knife and something that you can practice your sharpening on.
I'd say for a first-timer, spend the money on something better at first and maybe buy the Yamashin to play with once you know what a Japanese knife can be capable of. That being said, even the Yamashin will out perform many western knives out of the box. It just isn't to the same level as some of the others.
Now if you'd shown up earlier I would have said grab the new Goko damascus 240mm, but it was sold out in like a day at $99 each. lol I have a feeling it would still be a nice knife at the full price of $150 if Mark gets any more someday, but at $99 I think it was a steal and apparently a lot of other people felt the same way. lol
Here's the Goko Damascus 240mm to drool over even if it isn't in stock anymore (cruel, I know lol): http://www.chefknivestogo.com/goko.html
Edit: Well, a whole convo has been had while I typed this, but I'm posting anyway! LOL Yes, get the Kohetsu! It is one I have been looking at myself, but I just lean towards the Goko for its mix of performance and looks. It would not really be any better or worse than the Kohetsu for the price, just a different knife.