The key word I saw from the OP was "cheap." I agree, a Z-finder is better suited to the task, but it's gonna run you $400.
A 7" SD monitor will work fine for getting shots into focus. I learned the hard way that it's certainly better than using the 3" built into the camera. Is it as good as HD? No. But when you're poor like me, a $70 LCD is a more viable option than a Z-finder.
Spinner, it depends on your camera. I have a JVC GZ HD7 that has a regular A/V out, a component out, S-video out, and HDMI outs so I can hook it up to just about any tv or monitor. Look up what your camera has and buy the requisite cable.