That’s a pretty bad mindset to take considering what the corp likely does for you. I’m in a corp that’s pretty heavy industry in null (I should know, I more or less lead the production side of it). We have things set up as folows:
Ore/PI : 100% JBV (jita buy value) - We save on shipping, you save on hauling.
Salvage : 90% JBC - There will be a lot of overstock that we simply wont use and the stuff we do we wont get enough of. This is more to help newbros than it is to help us.
T1/meta modules : refined JBV - Helps fill some doctrine fits, and we at least don’t take a loss. Again, this is more to help newbros than us due to most modules being worthless to us.
Moon goo : 80% refined JBV after moon cost/extraction cycle. We pay for the moons so that comes off the top. Then 20% goes to corp for fueling our dozens of citadels, towers, SRP, etc. We don’t even ask them to haul to a refine citadel, we do that for them. If you wonder why that’s a perk then you must not have mined any long cycle moons before.
My corp manages several dozen citadels, all of which take fuel and had to be fit. We also have doctrine subcap and capital doctrines on hand our members, all of which was paid for by our industry and moon goo programs with the aid of buybacks. We also offer discounts of super/titan builds to our members which is again, covered via these programs. We have other perks for our members, but the point is the money has to come from somewhere and a lot of the time that comes more form the hard work of leadership than our members willingness to sell at a discounted rate to the corp.
If a corp does not have an industry wing, then it will depend more on taxes and lower rate buybacks to provide similar perks for it’s members. It’s just that simple.