While you are researching your options on boats, start working the gates in the boat you have. The training will help you learn that regardless of the craft, you should be able to make the moves. And don't be intimidated about gates. Just start trying to run through them. And then begin setting up a sequence for yourself using upstream and downstream gates. And at times when there are "real" slalom boaters at the gates, watch their moves and how they set angles. Remember that everything you are learning for running gates is applicable to your boating--whether you are a river runner, creek boater or play boater! And during the cold winter months running gates is a great option because you tend to stay pretty dry.
Boats - you have some good leads already. In addition, Fluid has a great plastic slalom boat, the Donsa, which gets big thumbs up from slalom racers.
Finally, we have a bunch of articles on the Endless website that talk about slalom/river running you might enjoy http://www.endlessriveradventures.com/news?showarchive=Technique%2FSkill+Development.