Most people love to talk about themselves and what they do...
(If you're having an awkward silence at a party, just ask the other person something along the lines of "What do you do for a living?" or "What do you do on your spare time?")
After reading your question and formulation a couple of times, I believe you would get a better response if you changed your attitude/approach slightly.
The way I read your current approach, is that you have job to do, and you just need some users to "serve you with information". It's like "I need you to answer my questions, because I need to know more about you".
You should use an approach like "Hey. Can't you show me how you do this? I'm all new to this and I would love to know how you manage to accomplish all those things?" During this informal "interview", you could drop in a few "do you think that would have been better if it was done another way?" and "what's the biggest pitfall here?"
Although I do like your question, it is a bit broad. Because you don't say anything about your intention with this user research. What are you trying to find out, and what are you going to do with your findings? That is really α & Ω when you're working with UX.
Always know why you are doing something and what it's for!
- If your intension is to analyze something (task analysis, user analysis, workflow analysis etc), then you should consider to use another data collection method. Ie. interview instead of survey, or even observation instead of interview.
- If your intention is to involve the users, then you should consider to go all the way with "participatory design" - let some representative be involved in everything (meetings, voting, budgets, strategy etc).
- If your intention is to evaluate some prototype, then you might consider to use some other method that doesn't involve users (expert review, cognitive walktrough, heuristic review, GOMS-analysis).
- I doubt that your user group is so specific that you won't benefit from testing it with other people. Lots of research suggest that DIY-testing (ref. "discount usability") gives you very valuable information.
- Since they only want to use "fully functional products", you might consider to deploy the product feature by feature (aka "vertical prototypes" ;-) ... ).
Oh, BTW: Why not let them try another software and ask them to compare pen&paper vs software. There's no need for you to do the same mistakes others have done. A competing product can be a perfect prototype ;-)
