There are a fair number of used E/F spinners on the market. HOWEVER, if you have a J style spinner, the cheapest solution is to suck it up, contact LASAR and BUY A NEW SPINNER ASSEMBLY. They have the absolute best prices on them. I cannot stress this enough. I have THREE cracked bulkheads sitting on my shelf from the years. If you are lucky enough to find a used bulkhead for a J style spinner for a Hartzell propeller, it will likely have a fair amount of time on it AND WILL EVENTUALLY FAIL. The new design mounts directly to the hub and not the flywheel and does not use the cheek plates. There is fairly tight clearance (~1/16") between the trailing edge of the prop blades and the openings in the spinner dome. This is normal.
One of my cracked bulkheads was one that had been repaired and failed within 10 hours. The other two I believe cracked after around 400 hours each because of a combination of age and fatigue, and improper mounting and vibration. It is important that the spinner be tight on the hub, especially with the older style spinners that have the bulkhead that is mounted to the flywheel. Both times when pulling the spinners after the "non-repaired" bulkheads cracked, they were clearly not on very tight. The mechanics who mount them tightly that I've seen place a ring of tape (teflon, copper, et cetera) around the hub where the ring on the spinner attaches. Those little "cheek plates" that are inserted under the spinners fail also and tend to run $300-$500 IIRC.