It is worth zero. This is an example of what lots of newbies do, and I see that you are not a newbie. People often rearrange words, or ad an "s" to names and think they are valuable. The name is awkward and it just looks wrong and sounds wrong, so that would be confusing to people.
To me, this is similar to what people try to do with names like DallasRealEstates.com or RealEstatesDallas.coom. Those names are wrong. Or, something like PlayPokers.com, which is another name that is wrong. maybe a better example would be something like RepairsCar.com.....it just doesn't work. There are plenty of analogies that would be better than mine, but the main thing is that when you see the name is just isn't right.
For you to even say that you "think" that PropertyFinance.com is better than your PropertiesFinance.com makes the point, I think. You have to "know" that PropertyFinance.com is better than PropertiesFinance.com. By even allowing the possibility that your name is as good as the other detracts from everything you say, and leads one to believe that your judgment is wrong when it comes to this name.
When people ask for educated appraisals, it is usually an attempt to try to keep low appraisals out, and it is kind of giving a wink and a nod to those who might be inclined to agree with you to come on in and join the party and give a nice appraisal, since they share the wonderful insight that it took to come up with this name.
You also say that there "appears to be a lot of companies with "Properties Finance" in their names. Just more talk that detracts from everything else. Weak words like "appears". I mean, you obviously checked Google, so what did you see? Don't be afraid to say that you say a "ton" of companies with the words in their name.
I am being extremely harsh because these types of domain names are lazy names, and they really go against everything that is fun and profitable when it comes to domain names. And everything you say leads one to believe that the name is weak......and the name is extremely weak, anyways. You cannot make a wrong name right. It doesn't take a lot of effort to mess up a combination of words and come up with something like this.
My appraisal is zero, and others can come up with their reasons why it could possibly be worth something and I still won't change my mind. To me, this name is the worst of the worst because it goes against everything that makes the domain business intellectually challenging, exciting, and profitable.