Sun's MIDP for PalmOS is a good place to start. I have used it and it can get smaller jobs done.
If you still want something for free and you do not mind a 100MB download, you might want to take a look at :
IBM's WebSphere Device Developer In earlier versions, this product had some quality problems, but it has gotten better.
I do not think that Sun is going to do any more releases for Palm. This morning I submitted a question to
Sun's J2ME chat about a new Palm release and the response negative and suggested that Sun expects the other vendors to pick up the slack.