HBC is usually more expensive for the same parts that can be purchased elsewhere. Example: BB valve covers are way over priced when compared to the exact same ones sold by Crane Corvettes (both eBay pricing). Do your shopping.
Unless they (HBC or anyone else for that matter) have a truly one of a kind, hard to impossible to find part that you must have, keep looking.
Also, do not believe an item sold for XYZ usage is actually correct. Many times it isn't. As other have said here, post the URL for review.
For an example about HBC pricing.....for some time now, I have been watching a NOS Y55 battery on HBC with a price of $1650.00. I recently found and bought one identical to the HBC battery for a fraction of their price. Like Mike said, keep looking and keep doing your shopping. Also, as Chick stated, keep doing your research. You may be new to the hobby but one of the keys is to continually research, research, research. Don't ever quit looking for parts as well as information and if you still have questions, just get on here and ask.