1) you should never assume the chances are small .. that sets you up for failure before you even got started. Imagine going up to a girl and saying "how unlikely is it for me to get your number?". #rejection

2) Many people have raised money outside their country of residence so it's possible. There's a few sites that are starting to aggregate investors; www.angel.co | http://gust.com | https://fundersclub.com

3) The best way to raise money is to get advice from someone who's done it before in your situation. So has anyone raised angel $ in Bulgaria? (Yes). Find them, ask for advice and do what they say.

Hope that helps.