Spacemonkey! said...
Pretty much any skim board will work fine for what you describe- I have used 5$ ones from reject shop and been able to ride upwind pretty easy. Really you want one with enough volume and length you will pay a little more. Obviously the foam ones would be a little better but more pricey.
If your going to be riding flat water though I would recommend getting a wakeskate easier to do tricks with etc than a skate and the upwind is almost as good. I ride an airush skate but I'm sure there are a lot of other good skates out there. Something to consider
I have a old (boat) wakeskate sitting at home, how they go compared to kite skates?