Fun/relevant story about my filter. At the height of the shortages, it came with the wrong filters inside. Somebody put the wrong stickers on them at the factory and everybody down the line went by the stickers, not the confilting stamps in the cartridge plastic.
The random pool store I bought if from couldn't grasp the concept that the stickers were wrong, so I pulled them off and swapped them. I pointed to the factory stamps to prove the actual model #s and they still couldn't grap it. They had the Pentair rep come, who *also* couldn't grasp it, but agreed they didn't sit right in the housing. (Because. They. Weren't. The. Right. Filters.

). So instead of just swapping the filters, the Pentair rep took the whole thing and replaced it entirely.
My filters are expensive and I would have been out $1000 for new carts. They wouldn't have given me the time of day if I had purchased it 2nd hand, even though it was never used.
So, obviously, you are looking to recoup as much money as possible, but if my 2 choices were retail price with no warranty, or retail price with a warranty, I'd buy it from the store. Somewhere in the middle is a happy medium, but that risk to cost ratio changes for each prospective buyer. For some, not paying 6% in FL sales tax is enough. Others would want a sweeter pot.
List it on FB Market place, CL and the offerup app to reach a larger audience.