I have been thinking about how to address this without leaning into some IC data, but it is simply not possible. So if this goes to far feel free to delete.
The issue I have with the current model of the second hand cyberlimb market is that there is simply not compelling savings over just getting a limb, unless some very particular things align.
People have quoted some prices here, so a limb 8k'ish processor 6k'ish. I think both are in a good place in terms of price. Despite what has been said, 14k is not entirely impossible, but it is enough of a sting to some to make them realise it is bad.
Now we look at the second hand market. Legitmately installing second hand chrome costs you 3k. Illigitimate pricing may vary but likely to be around the same spot. So that is already 6k just on install fees. Lets say second hand limb and processor currently go for half what they do we are talking about 4k for limb, and maybe 1-2k for processor. So around 11-12k.
Now if we put NPC's in the mix with limbs you can rip, you need to pay a ripper doc to pull that chrome, and install it.
So if you are friendly with a ripper and get lucky on an NPC then yes, you likely could make a saving on a limb. But honestly that is already a big potential.
Limbs have some of the smallest mark up of any cyberware, practically get installed at list price. So there is little fat to trim in terms of savings.
This is not to mention custom limbs which are a sure fire way to get who ever lost it come hunting you.
NOW, some, myself included might look at the above and see the potential for RP here. Befriending a ripper, befriending a solo or of course hunting them out and paying the to get you a limb.
I think for me and my extensive and well-informed experience of this particular topic almost always points back to 'there isn't enough to be saved going second-hand' or 'there isn't enough to be made going second-hand'