The purpose of the table is to allow players to pick and choose from the various features, and thus design their homes or castles, increasing the thickness of walls as necessary and so on. But the purchasing table allows for something I'd never remotely considered before.
Note, if you will, that the Purchasing side indicates what the local town (according the principles I described in the earlier post) is interested in buying. And note that the products in this case are not things that are easily carried. For example, the town is looking to buy 4 sections of roadway, 30' long and 10' wide. The town is willing to pay 155 g.p.
In other words, the town needs a road to be built - or possibly rebuilt - and at present there's no one in town who's able to build it. See? The selling side indicates clearly that no road-building can be bought.
Oho! All that is needed is a capable, willing party - including one that's a mason - to spend some time laying out the necessary road and earn for themselves 620 g.p. Not only that, but apparently the town is looking for a plasterer, some wallbuilding and even a sculptor to do a little work on a freize (obviously, for 5 g.p., they're not looking for a high-quality artist).
Now, I'm not suggesting that ANY party has the slightest interest in this sort of contract work, but hold on a moment. Just where exactly is this road that needs building? Is it critical? Would it encourage them to see the party as one of their own? Or is it possible the road wanted it between a local high mucky-muck's house and the county throughfare?
Laughable it may be, but for a low-level party I see this table as an opportunity for connecting a player to the local area and a way to make some coin on the side without having to take someone down in an alley.
For a high level, I see it has the kernal of a longer, larger table, with many more objects added (a bridge, a tunnel, a wharf?), providing the basis for the Lord's followers to earn a steady income. No, the player might rather adventure, but how about it if the secondaries spent the intervening summer rebuilding part of the city walls, or steadily laying a road to the next town?
Something I never intended, or thought about ... but here's the basis for calculating what it would pay. And not for just in Masonry either, but for foodstuffs, mining, trapping, animal husbandry ... everything, in fact, because that's what my equipment table is meant to cover. Everything.
No wonder I fuck around with these things.