Going up and down the gravity well is expensive as all hell. You'll never make that back no matter what you find on Ceres or the Moon. Even if it were already stacked in refined bars waiting for you to pick them up!!
OK as a fully subsidized mission with no profitability other than a technology subsidy, sure. But as a proper business? No way.
At least not until we get that space elevator built
There are several projects to build a space elevator until 2050.
I think cost estimates were around 50-100 billion $ with usage of graphene or similar super materials.
It's hard to put a cost estimate on something that doesn't exist. No material has been found which has anywhere near the required strength to weight ratio.