If you look on ebay there are tons of just cameras. The issue with getting a better camera is typically weight. It's not just a matter of whether you can lift it but also how much does it affect flight?

I have 3 different cameras, the first is like yours, the second is flycam1 and the last is a small 3in1 w/ onboard memory. I typically prefer the last two as there are no interference problems and the picture is better.