For me this is dice: 1d6+6 means roll 1d6 and add 6, like in traditional roleplaying games. You probably already spotted this, but just in case i explicit it.
So the last one might be the number of items available.
The 1_100 could be some kind of scale, adjusted by another dice roll? Maybe it's why you don't spot multipliers?

That's very ingenious, thank you! I don't do role-playing games so didn't spot it. So 1d6+6 means basically, a random number between 7 and 12. Minimum 7 because a die doesn't have a "zero", the roll will be between 1 and 6, plus 6. Kind of a roundabout way to do it in a computer algorithm, but what do I know.

I'm going to test this. I'm gonna dock and undock with Crassus a bunch of times and see what it offers.

Well, not that simple. I went back and forth between Crassus and Penitent, noting prices. There is something going on but it is not obvious what.
Crassus offers four commodities coded thus:On six visits the offers were I was going back and forth between Crassus and Penitent, which has three commodities coded(i.e., identically) and their prices were very similar.

A couple of things pop out to me. Considered as die rolls as @Dr_Bicinium suggested, the final item could account for quantity offered: "1d2+2" for the quantity of rwaste, "1d8+8" for the quantity of scrap, "1d6+6" for spirits and "1d2+0" for having either 1 or 2 organs.

The first item, an integer, must be related to price, for example "rwaste,-2" and rwaste is always a negative number. That integer is proportional to the price (6 versus 25-30, -2 versus -5, 1 versus 5, and 54 versus 480-270), but it must be perturbed by another factor which I don't see.

Scrap and rwaste are very stable, which suggests that the die roll in the third position is not applied to the price. If it were, the "1d2+4" would be moving the price of scrap away from 5.

That's all I have for now.

You're welcome, happy to help!

I guess there is at some point a low and a high value for price, and maybe for quantity too. I mean the way trade is usually done, one system produce a good and another needs it. So we should find that difference in the scale too. At glance, the 1_100_5 makes me think of it, with a low integer first (1) and a high in the end (5). The 100 makes me think of a kind of percentage, or threshold. But considering your logs, i can't see a relation.

Maybe it's the same low / high stuff for the quantity, with one xdy+z for min and the other for max? But it doesn't seem constant, although the fact that the two dices are equal for spirits and organ must mean something.