My 29's are earlier, but since you asked for opinions . . . my observations are based on the described 98% condition, 4" barrel, and pre-lock/post-endurance package era dash 5.
From what I've seen the current market would seem to be that anything less than $600 would be a bargain. Personally, I would be inclined to start losing interest (if I was in the market for such) when it approached the $750 to $800 range, but the fact that I already have my 4" 44 may be coloring my judgment. Some folks seem to willing to pay a bit more for certain guns and this one as described would certainly seem to fall into the 'desirable' category. If you don't have one and want one, the "gray area" for what you're willing to pay is only defined by your conscience and your wallet . . .