I would try to pick up one used (new trainers can cost as much as 300 bucks, you can buy a used 9/12m inflatable for that much!).
Best place to ask is probably www.powerkiteforum.com
in the wanted section. You should be able to score one for under 100 bucks if the market is good(changes all the time). I'd go 3m.
I scored a prism p3 for 40 bucks on sierra trading post a year ago; maybe some are still floating around on the internet. try to get something with a bar, but don't be too picky. The trainer is really just to teach you how kites move through the wind window, and some basics on power.
I'll leave other people to make recommendations, I always proscribe too much kite. I will say it's a wallet heavy sport as you're breaking in. You can cut corners and go too big too soon, but it's probably just a matter of WHEN you're going to get hurt. I got ROCKED early on, and that taught me some valuable lessons about modesty. I still lovelovelovelovelove to kite, but my progress is probably slower because I didn't have lessons. like, I just learned to effectively loop my kite without killing myself; and I'm STILL too heavy on bar pressure after turns/jumping.
Still, it is something you can learn on your own if you're patient. Expect to spend atleast 800 bucks/ 2-3 months before you're cruising on your first larger kite, and thats probably just for starters.
Try to buy used until you're intermediate/advanced, you'll save so much money, and you can score some SICK deals if your timing is right. Without lessons you're just gonna beat the crap out of your first kite anyway.
GL. You're on the right track