I was in the same situation. When I had to get injections weekly, it was 15 buck a pop to see my Dr.'s nurse. The test was kept with me or there it didn't matter, then it was my wife the accountant that said that's not the way to go. So she volunteered to do the injections and they gave her a pratice butt foam thing.
Soon it came a time when it was her that would do my injection. She did get it in and freaked out and left the needle dangling in my ass
So the nurse had to calm her down and made her finish the injection. Took two more times supervised and she's now a pro at shooting me in the shoulders and glutes. I haven't tried any other place. The chest sounds intresting but scary.