It sucks but you have to pay for historical stuff beyond the month.

However (someone can correct me if I am wrong) they get the data they post from the fishwrap, (SD Union) so if you find the day of the month that the union prints out the data, which is usually like the 10th-14th or something like that, then you can start going back month by month.

This is a guess mind you assuming that the union prints this stuff. Maybe they do not and send it straight to dataquick but I would be willing to be a few clams that they print it out.

Esmith as posted a link to a site that has all recorded sales for the county and I have gathered data from that site before. If I remember right they go back a few years at least. Look back a few days in the posts and you will find it.