dScope and Audio precision are indeed commonly used by profesionals. Apart from very good specs, these are mainly used because of features like automated testing and reporting, which is not so important for hobbyists. Also, as a professional, 10 of 20k for something you use on a daily basis is much more acceptable price wise then to a hobbiest who uses this max half a day a week and who gains no profit of it.
As to jitter, I do agree it is not so easy to measure accurately, but I do not agree this is very important for audability. I read of a controlled listening test were they introduced jitter in the audiochain, and asked people to indicate the level of jitter. In essense, people only started to recongnise the jitter because the DA was creating skipping sound when the jitter was so worse. I have searched for the reference in my archive, but could not find it. As far as I remember, the study was performed with members of a dutch audio forum.
Anyway, somehow in audio people tent to believe that our ears/brains are a much more sensitive instrument that high end measurement gear, and that stuff that can barely be measured accurately, make a "huge" difference in sound. My opinion is that the oposite is true. When it measures okay with reasonable quality gear, it is also ok. This means that is you built something with moden electronics (pre-amp, amp...) normally most well designed gear will "sound" exactly the same.
Things change however when you measure the combination of loudspeakers the acoustic environment they are in. When you start measuring reflections, power responces, decay times... you will see HUGE deviations from the "ideal" (currently there is no concensus about the "ideal" however, as to little is known about the phsycho-acoutics of the brain).
The point of all of this is that with quite low cost gear you will be able to measure the actual REAL problems in audio as a hobbyist, solving them is a lot more difficult however... Don't spent to much money on gear, but buy some good books on the subject instead.
Some good reading on the subject that is freely available:
http://www.davidgriesinger.com/http://gedlee.azurewebsites.net/Books/AudioTransducers.aspx