The "Poor Man's Spectrum Analyzer" is still alive and well. Here's the URL:http://www.science-workshop.com/
The other posters are correct regarding your budget vs. what you can find surplus. You might also take a look at the work done by W7ZOI for a better instrument than the one from Science Workshop...point your browser at:http://126.96.36.199/cotton/SA1.html
Depending on what your host of other test equipment is you might want to consider a service monitor that contains additional capabilities depending on age and manafacturer. I shopped around a few years back and picked up a used IFR unit that has a built in spectrum analyzer, RF signal generator, sweep and tracking generators, and many others. Do a google search for "service monitors" and you'll see lots of examples.
GL -- Dino KLØS/4