Essentially, you are looking for a cheap source of minerals, which is fair enough many indy players work this way. But any omega miners who know their way around the market won’t be interested as refining/hauling/selling is already factored in. So you will be relying on newer players who just want to sell for quick isk but you will soon hit a capacity problem and won’t be able to hit your targets.
You would probably be better setting up a slew of buy orders but this can be time consuming and collection/hauling is a major bind.
As you are based in Rens then I would try the ice miners in Abudban (and elsewhere), many ice miners also mine ore when the anoms are not up and often you will find a few in the same corp. Talk to the corps and see if you can negotiate a supply deal but you’ll find the margins are tight even so.
If you really want a regular supply of bulk minerals then you want an Athanor on a good moon and a cadre of miners ready and willing to pull maximum value out of the belts on a regular basis. This also means recruitment is important as you’ll see a turnover of team members over time. Of course you will also have to be prepared to defend your structure and rightly so