Thanks for sharing - I find that really interesting about budget.......with sales I have always established a potential clients budget range and I have not done to badly.....
IMO asking for a maximum budget does not show weakness it helps establish if you are wasting your time - if they come back and there is only a couple of thousand between their best offer and your price then there is potentially some wiggle room - if they are playing games or genuinely can't afford it, then tell them their budget is to low and walk away - you have established they can't afford it or they won't admit they can - job done, move on and forget about it.
Domain selling might need me to have a little re think on this as you have a very good track history