I need a pointer to audio software tool(s).
I am looking for a low cost (of course!) software utility that is able
to locate a short, specific sound sequence within an audio stream
(e.g. audio line input, internet streaming audio, etc) or within an
audio file (e.g. WAV, MP3, etc).
The search parameter should be a sample of the same sound sequence
that is being searched.

After locating it in the stream or file, the program should either -
a) stop at the start location of that sound and allow the rest of the
stream/file to be played from that point onwards, or
b) even better - time stamp and (re-)record the stream/file from that
point onwards - for a user-defined length of time - into a new sound
file.

To illustrate:
Let's say I want monitor the radio for a particular jingle and as soon
as I hear it, I would like to listen to whatever comes next
immediately after that.

I see two posibilities:

a) The hard way.
I could manually time stamp and start recording a continuous audio
stream (say twelve hours) into a large sound file. Then, using an
audio file editor, locate an occurence of the jingle within the file,
mark it as the search sample and then search the whole file for each
occurence of the same sample. Once found, I would listen to the
sequences. I would calculate the real time (absolute time stamp) of
the jingle by relating the recording start time with the timer
location from the recorded file. After that I could get rid of the
file.

The challenge here is to find software that has this kind of "sound
bite" search facility for a given sound file.


b) The elegant way:
The software is given a sample of the jingle and then it would
continuously "listen to" the streamed audio input. Once it "hears" the
sample, i.e. the jingle, it would time stamp the event (based on the
computer's clock) and start recording for a user-defined length of
time into a new sound file and then continue monitoring the audio
feed.
Here it means finding software that has this kind of sophisticated
monitoring and recording capability.

With low cost I mean no more than the low 100s (in dollar rates),
depending on quality and features and preferably under $100.

To summarise - I need to know where to find a low cost software
utility that can handle either of the above methods, preferably method
b).

Any takers? Helpful answers would be very much appreciated.
Oh, and by the way, NSA need not apply - too expensive   ;-)

An old programming motto says "Do not compare floating-point values
solely for equality".

I suspect you need to compare sound samples for SIMILARITY which is a
more woolly idea.   Where most sound files are concerned you will have
to effectively play them anyway to convert them from compressed form. 
This is a lot more work than searchibg for text strings in bulk data.