If you just want to play around, don't feel like you have to spend tens of thousands of dollars. But you should understand that as your demands grow, there are systems out there today that will meet the challenges. I believe there are three main families of nonlinear systems, consumer, prosumer, and professional. Where you draw the line has more to do with your own tastes and biases. The first and most important criteria is the image quality.
All nonlinear systems use some form of video compression.
Even today's modern DVC camcorder format uses compression in order to pack more information on very small tapes. All of these compression standards are lossy to a certain extent, which means that the picture will never be exactly the same as what you see through the camera, but varying degrees of fidelity. Mostly because of this bottleneck, the video quality suffers. Systems like these are very cheap, but the images are blocky, not usually full resolution, and some don't even reach 30 frames per second. Systems like this are more toys than anything else.