Network Analyzer

I want some opinions of DIYers out there.

How much would you be willing to pay for a small, portable USB-based Network anaylzer that you could hook to your PC? Something that could do frequency/phase plots of your amps, pre-amps and filter networks. Maybe even it could have a THD measurement feature. Not something Ultra-high end but medium resolution for the average hobbiest.

Thanks for you input.
Frequency response measurements can be done with Speaker Workshop (from using a duplex soundcard for input and output. Obviously, the quality of meausrements does depend on the quality of your soundcard inputs. I use a Turtle Beach Montego2 with very good results.

To measure the electrical frequency response of a network, simply use the MLS output to drive your network/amplifier/active crossover and use a probe instead of a microphone to measure the system output. I've used this excellent software to taylor the frequency response of my three way active crossover. I've also added clamping diodes to the input of my soundcard after accidently frying my SB PCI512 with +15v from an op-amp power rail....

SW can also do THD measurements (THD vs freq, THD vs power and THD vs ??) but I haven't received sensible figures using it so I'm not sure the function works correctly.

Nice one.