Replying to Poor Kid Wants a Good Camera

I've been getting really into filming lately, and as the ski season approaches, I am really looking forward to dank edits. The problem is that all that I have for a camera is a gopro hero 3, which I love but just doesn't produce the video quality that I'd like. I've been looking into SLRs lately but they are very expensive and the most I want to pay is around 300 - 350$. Honestly, the allure of having an SLR is something that's influencing me, as you look legit when you have one. I'm a high school kid so unfortunately the budget is limited. Any feedback is appreciated.