As with a lot of things in life, stick to the clear facts and analyze them. The true value will come forward, and if the seller does not agree with this and inflates the price for other reasons (ie ego, pride etc), id look elsewhere for a deal.
I do not yet own an IP, so please forgive my ignorance if any.
If the residex report (or equivalent) suggests the value is less than what's being asked, it doesn't hurt to mention it to the REA.
They know (and you know) that theses reports are only estimates - but it shows that you're dilligent and have put some thought into the value of the property (which often adds to your credibility as a serious buyer).
You could also be a massive pain in the a*s at the open house and continue to blurt out the low value residex placed on the home - might deter a few people
I might pay a guy from a valuation panel to go over a have a look see.
Ive found with large lots that the owners usually say "chuck a bunch of houses on it" ...It comes out the mouth so easy. They dont realise those are million dollar words with years of work and high risk.
Im not trying to devalue a property per se. Im just trying to bring it back inline with reality. So hard when your dealing with speculators.
They are good people im dealing with. Old couple who have been feed alot of bull. So i think ill get a Residex, APM, and HomePriceBuyers report so there can be no doubt