Look around your area for composting facilities. In the US, they usually give it away for free, especially if you have a required community compost pickup program.
There may also have a quarry in the area that will let you grab refuse like shale or slab gravel you could use, but the consistency would be the key there.
Blacklists using IPv4 as reference usually expire old addresses after a period of time for this reason. You can also find your IP in any lists and request to be removed if you can contact the maintainer. If you're using a shared IP for ingress or egress, you're kind of SOL though. You need to get a dedicated static IP from whomever your host is to help prevent this from happening.