If you want a digital analyzer look at this: http://www.saleae.com/logic/

I 've got just the right moment and solved a problem that I had for 4-5 years!

It was a glitch that I could not catch it on my Tektronix TDS2012...

Then if you want analog signals, follow what Melanie said and find a decent equipment even refurbrished (It was the AFG3022 that I got this way).

Ioannis