The rate is negotiable. The advantage of dealing with us is that you would have a consistent cash buyer and all the perks that come from private cash purchases which is appealing for some miners. The problem with using an exchange is that we need to be banked and banks aren't willing to onboard a bitcoin company like mine unless we do really high volume. As we are still a regional operator, we don't yet have the volume required to be banked and therefore be able to use an exchange. This is why we have typically sourced from miners and other ecosystem participants. However, we've outgrown our current sources and need to cultivate additional relationships.
Coinbase would be happy to onboard you. Chase would also be happy to be the middleman for your cash deposits before they land on the coinbase exchange (no matter the revenue for both) . And they are
both FDIC insured. Do you have an LLC? Not having one at all complicates things and makes it look like your laundering money to small banks/ credit unions (even though you probably are not) Majority of your "sovereign citizens" can't hide op sizes you are aiming for, You've entered new territory people with the BTC capitol you seek know you make %8-11 a sale and dont care about how much your paying vendors so if your pocketing 4-8% and trying to squeeze a little more profits for trades you are going to be hard pressed. good luck !