There are avenues like wholesalers and bird dogs, but I haven't had much success with them. You have an ok game plan if you are making offers on REO's. That's all I would focus on unless you want to wait for Short Sales, but that can throw your timing off.
15k is kind of tight. You can get that eaten up pretty quick. Every house is different so if you're saying 15k NET then your numbers might work better, but just saying buy at 100k and sell for 125k or something like that is going to hurt you.
Stick to your numbers that break down what the property needs and what it's going to cost for you to get it, hold it, fix it, and sell it. If you are being realistic, DO NOT GIVE IN! Just make more offers or look for more deals. The minute you try to make a deal work by offering a little more or something like that you get burned.
I know it's tough when you haven't seen one through to completion, but when you do, you'll be glad you stuck to your numbers.