I'd say it's definitely worth $30 to get the xpack and destinies. It's been on sale once so far (75% off!) so wait for the next sale on it and grab it. Even 20% off ($24) would be good.
Short of that, destinies for 995 TP is a definite, though I can't really imagine leveling from 20 to 25 without the xpack. Lots and lots and lots of quest repeats. Lots.