Entry-level camera/camcorder for video recording

College student (finance major) using a D3100 for photography/video recording and am pretty pleased with how HD videos come out.

Budget: Sub-$300 and a longer term Sub-$6/700

Size: Small, smaller than DSLR but if it's a camcorder, doesn't really matter

Usage: Video Recording, moving shots (in cars), active shots (parties, golf swings, running)

Reqs: 1080p >30fps recording, Decent mic? with the form factor not expecting much

Summary: College student that record random hobbies/events. I'm looking for a video-side replacement for my D3100 which seems to be more photography based. I love how the D3100 captures video so something of the same quality or better at less than 300 or 600.