What is the cheapest system to record the video from a security camera i just bought?

What is the cheapest system to record the video from a security camera i just bought. I bought it on ebay its a 30 led color security camera with audio and i can connect it to the tv but i need something so it can record the video and also something cheap im new to this because someone threw rocks at my window randomly and we thought it was gunshots. I tried a vcr but it dosent record for that long