[sdiy] Soundcard spectrum analyzer?

[JH.]

Hi,

I'm looking for an unexpensive way to measure a frequency response.
I've seen there are a couple of shareware programs that use the soundcard of 
a PC to both create a stimulus signal, and to measure the response.
Does anybode on the list have experience with one of these programs?

I'm looking for something to measure highly resonant filters, and I'm not 
sure if something that's aiming for the Audio / HiFi market is good enough, 
with short chirp signals and all.
I'd feel more confident with something that sweeps very slowly, and measures 
with a small bandwidth filter - or whatever the equivalent in the digital 
domain would be.

Can you recommend anything? (Price range 50 ... 100 Dollars, or is this 
unrealistic?)

Thanks in advance,

JH.