Aircraft are cheap because there is hardly any market.
They can also be too cheap, if the seller lacks confidence from looking at the current adds and concluding that his plane is not worth anything... have seen that too.
Frankly, you can't judge any add, any plane and any owner unless you have had expert advice on the plane in question. And before you buy, there is that all important pre-buy inspection. Without it, forget even looking at planes.
From afar, this AA5 looks like it is not badly priced for what it has to offer, in a normal marketplace it could make much more, but this is no normal market anymore. This plane is looking for someone who either wants to fly cheap as is (and put in a Trigg Radio in 2 years time) or someone who has been looking for a Tiger to make his own.
But without a serious inquiry, this is simply a game of guessing.