First of all, with the mining idea:
Is it even possible? How would you make a system that detects how much ore there is in a cargo hold? Would it take credits every time a rock is hit? Would it take credits from a trader who is getting filled or from the miner? What if the miner mines ore then drops it into space?
Sounds like a mission and a half to even try to code. Ofc me not being a coder, I could be completely wrong.
Then you have the issue of what faction gets their commodities nerf'd, sure people that RP Synth factions might be grateful for the huge influx of newbies to whom they must teach every aspect of the game, but what about when the newbies find out that there are routes that are more profitable? It's going to suck for those factions when everyone is leaving because every other trading faction is 100x more profitable. Or did you mean that we should keep the profit margins the same? In that case why wouldn't all the people who say 'its cheaper to die' just end up trading synth paste anyway?
This seems like a lot of effort for very little, if no gain. I'd be more tempted to file a sanction report for OORP lines in local. If they are going to sit there and die because someone ruined their power trading experience then they can at least put some RP into it and act like they are suicidal or want to try and fight their way out of the situation or whatever really. After all 'it is cheaper to die' is OORP and clearly making reference to the fact that they'd just respawn if you blow them up.