not to play the parrot...but: BUY A GLOCK as your backup. Used it will run you 350-400 and you can probably get 50-100,000 rounds out of it depending on it's prior handling and specific model.
If it's a question of ammo and classes, a flat sum of ammo isn't going to help much. Best investment you can make is to join a shooting community that will allow you to shoot with them and provide drills. Check your local ranges, but a good group will often just charge a yearly insurance deposit (50-100$ depending on group size and insurance guidlines) and a small range/class/target fee (10-20$) per event. My local ranges host a wide array of tactical, competition, and steel oriented shoots, and I haven't met a single weekly attendee who wasn't very good at his/her chosen shooting discipline.
A 1 day class will be a lot of fun, but probably is not worth what you will spend on it (just my opinion...instructors can tell you what you are doing wrong, but they can't build years of muscle memory into you instantaneously)