Wow, IMO that is a high price for that 09 GT, unless cars are just way more expensive there! In comparison, I paid $12.4K for my 2010 GT, 2 years ago, with 36K miles on it. It was $13.2 OTD. I enjoy it, but would REALLY love a 5 speed in it. I'm sure it would be much more fun if I could really control the gears. That is my one complaint about the car. But I had to get the auto so the rest of the family could drive it.
I'm sure the 03 would be more fun since it does have more power, less weight, and better gas mileage than the 09. If it is in great condition, it would be a decent deal. Most of the early Vibe GT's I've seen are around the $6-7K range, but they do have like 100K+ miles on them. I haven't priced any Matrix models in a while, but every time I have, they've been $1-2K more than comparable Vibes.
Good luck on your decision!