Brett,
I have made about 40 wood fly rod grips with just a utility knife, a small trimming plane, a hand held electric drill, and a piece of sandpaper. No lathe required.

Drill a hole through a rough piece of wood, slide the rough handle onto a wood dowel the same size as your blank, and then start carving. I do this more by feel than by sight; when the blank feels right, I stop carving. Sometimes they're not perfectly round, but then they fit my hand better than a round one does.

It you want a symetrical blank, I suppose you could cut out a guide from a piece of scrap wood that would have the shape and size of the handle you want, and you could rotate the work in progress against the guide until it matches. I've never bothered with that.

With sharp tools, I can make a cedar blank in 30 minutes. If I'm using a harder wood, it might take an hour. With a couple coats of epoxy, I have a nice grip.