I have performed some "manual" Usability Testing before. I is still very effective and definitely better then nothing. We had everybody in the same room. The tester, the facilitator, the documenters and the programmers. The hardest part is getting the programmers not to say a word and just observe. But I definitely recommend performing any kind of Usability tests! You always learn so much!
We have done low cost Usability testing, by taking our Equipment to colleges with user Manuals, and asking each interested students to perform small part or portion of the user manual for that product. Very great feed back. You will be surprised.
1- All students are educated.
2- You are getting different type of students that will target different type of economy.
3- You will get both Male and Female inputs.
4- You will get different age brackets.
5- Don't forget to provide some kind of goodies for them.
Useability Testing is usually about the useability of the application, while application users should participate in this they are also reknowned for using what they get due to many attempts and failures to get what they want.
montgomeryam is absolutely correct with his definition - user documentation and users doing testing (unless they are testing for how useable it is) have nothing to do with it.
I have not failed. I've just found 10,000 ways that won't work" --Thomas Edison