I'm not sure what exact item your looking at but I purchased a 4 point docking system and quick detach tour pack mount from eBay for my bike. Never had an issue. I always check eBay first, harley charges so much for their stuff and whenever I can cut Uncle Sam out of their cut I'm in.
I have a detachable 4 point tour pack docking mount I bought on e bay and never used, looks very nice, am selling it, I paid $100 for it, will sell it for $75 with free shipping. I dont need it because I bought a used tourpack that already had the docking kit on it.
I bought the detach rack that the tour pack attaches too off e-bay. One of the latches fell apart the first day. I replaced both latches with genuine HD and have not had a problem with it since. Don't know if I saved much after having to replace the latches.
at this point id be happy just knowing which mounting kit to get for a tour pack I would iike to mount for a solo seat. It would need to be more forward than the two-up configuration. Read many a thread on the subject but no one mentions any part #s!!
I was looking specifically at the kit from zlbackrestmaker. $265 shipped. Seems like a good deal if it's decent quality.
Based solely on your brief description and price it sounds like you're looking at an FBI Tour Pac mount. If you've got a pre '09 bike these are great as the eliminate the ugly hoops. If not, then you might want to provide a link so we all know what you're asking about.