As a practical matter if the tenant has any tactical sense (and it sure sounds like they may) they could probably challanege a scrivenor's error defense by claiming ignorance of the landlord's "big business" thought process:  "I thought maybe he had some reason for it, my friends suggested maybe it was tax issues, or insurance or that kind of thing or maybe he was doing something illegal and I would be in trouble if I said anything.

This was a scare tactic to get us to settle.

You mentioned "they are offering their system for AUD$3.5K", BUT, it is certain that they will be pressuring you with up-selling tactics which will require you dip into your bank account / credit cards more and more.Australians in particular are seen as easy targets for these type of programs, because we (yes, I'm an Aussie) are shocked when told we can get into three bedroom brick homes for $Au75k that rent out for $750/m.

More for your consideration:The following are links to information that the savvy investor would need to combine investment tactics and techniques to generate high yielding ROI.

I have done the general tactics as everyone else just seems like traffic is very slow.

Oh, and agreed that seeing if he wishes to buy it at a "favored" price--perhaps just a part of the commission--is good tactics and in some states the law that you have to make the offer. 

I'm pretty sure other tactics like saying "I only accept 11 month leases" because section 8 requires 12, are also asking for a discrimination lawsuit.My understanding on this (from lots of reading but no direct experience)  is that you can apply the same rental qualification criteria to a section 8 applicant as any other - credit score, prior landlord reference, criminal background check (except in seattle) and so on,  however when it comes to income you are only allowed to verify the tenants portion of the rent responsibility.   

@Victoria Colemanhttps://www.masslegalhelp.org/legal-tactics.

Idle scare tactic threats..... they are full of BS 99.9% of the time.

Hard to tell which tactic may or may not work.